forked from Minki/linux
52e9f87ae8
209 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Mel Gorman
|
c4a25635b6 |
mm: move vmscan writes and file write accounting to the node
As reclaim is now node-based, it follows that page write activity due to page reclaim should also be accounted for on the node. For consistency, also account page writes and page dirtying on a per-node basis. After this patch, there are a few remaining zone counters that may appear strange but are fine. NUMA stats are still per-zone as this is a user-space interface that tools consume. NR_MLOCK, NR_SLAB_*, NR_PAGETABLE, NR_KERNEL_STACK and NR_BOUNCE are all allocations that potentially pin low memory and cannot trivially be reclaimed on demand. This information is still useful for debugging a page allocation failure warning. Link: http://lkml.kernel.org/r/1467970510-21195-21-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
11fb998986 |
mm: move most file-based accounting to the node
There are now a number of accounting oddities such as mapped file pages being accounted for on the node while the total number of file pages are accounted on the zone. This can be coped with to some extent but it's confusing so this patch moves the relevant file-based accounted. Due to throttling logic in the page allocator for reliable OOM detection, it is still necessary to track dirty and writeback pages on a per-zone basis. [mgorman@techsingularity.net: fix NR_ZONE_WRITE_PENDING accounting] Link: http://lkml.kernel.org/r/1468404004-5085-5-git-send-email-mgorman@techsingularity.net Link: http://lkml.kernel.org/r/1467970510-21195-20-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
50658e2e04 |
mm: move page mapped accounting to the node
Reclaim makes decisions based on the number of pages that are mapped but it's mixing node and zone information. Account NR_FILE_MAPPED and NR_ANON_PAGES pages on the node. Link: http://lkml.kernel.org/r/1467970510-21195-18-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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1e6b10857f |
mm, workingset: make working set detection node-aware
Working set and refault detection is still zone-based, fix it. Link: http://lkml.kernel.org/r/1467970510-21195-16-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
599d0c954f |
mm, vmscan: move LRU lists to node
This moves the LRU lists from the zone to the node and related data such as counters, tracing, congestion tracking and writeback tracking. Unfortunately, due to reclaim and compaction retry logic, it is necessary to account for the number of LRU pages on both zone and node logic. Most reclaim logic is based on the node counters but the retry logic uses the zone counters which do not distinguish inactive and active sizes. It would be possible to leave the LRU counters on a per-zone basis but it's a heavier calculation across multiple cache lines that is much more frequent than the retry checks. Other than the LRU counters, this is mostly a mechanical patch but note that it introduces a number of anomalies. For example, the scans are per-zone but using per-node counters. We also mark a node as congested when a zone is congested. This causes weird problems that are fixed later but is easier to review. In the event that there is excessive overhead on 32-bit systems due to the nodes being on LRU then there are two potential solutions 1. Long-term isolation of highmem pages when reclaim is lowmem When pages are skipped, they are immediately added back onto the LRU list. If lowmem reclaim persisted for long periods of time, the same highmem pages get continually scanned. The idea would be that lowmem keeps those pages on a separate list until a reclaim for highmem pages arrives that splices the highmem pages back onto the LRU. It potentially could be implemented similar to the UNEVICTABLE list. That would reduce the skip rate with the potential corner case is that highmem pages have to be scanned and reclaimed to free lowmem slab pages. 2. Linear scan lowmem pages if the initial LRU shrink fails This will break LRU ordering but may be preferable and faster during memory pressure than skipping LRU pages. Link: http://lkml.kernel.org/r/1467970510-21195-4-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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75ef718405 |
mm, vmstat: add infrastructure for per-node vmstats
Patchset: "Move LRU page reclaim from zones to nodes v9"
This series moves LRUs from the zones to the node. While this is a
current rebase, the test results were based on mmotm as of June 23rd.
Conceptually, this series is simple but there are a lot of details.
Some of the broad motivations for this are;
1. The residency of a page partially depends on what zone the page was
allocated from. This is partially combatted by the fair zone allocation
policy but that is a partial solution that introduces overhead in the
page allocator paths.
2. Currently, reclaim on node 0 behaves slightly different to node 1. For
example, direct reclaim scans in zonelist order and reclaims even if
the zone is over the high watermark regardless of the age of pages
in that LRU. Kswapd on the other hand starts reclaim on the highest
unbalanced zone. A difference in distribution of file/anon pages due
to when they were allocated results can result in a difference in
again. While the fair zone allocation policy mitigates some of the
problems here, the page reclaim results on a multi-zone node will
always be different to a single-zone node.
it was scheduled on as a result.
3. kswapd and the page allocator scan zones in the opposite order to
avoid interfering with each other but it's sensitive to timing. This
mitigates the page allocator using pages that were allocated very recently
in the ideal case but it's sensitive to timing. When kswapd is allocating
from lower zones then it's great but during the rebalancing of the highest
zone, the page allocator and kswapd interfere with each other. It's worse
if the highest zone is small and difficult to balance.
4. slab shrinkers are node-based which makes it harder to identify the exact
relationship between slab reclaim and LRU reclaim.
The reason we have zone-based reclaim is that we used to have
large highmem zones in common configurations and it was necessary
to quickly find ZONE_NORMAL pages for reclaim. Today, this is much
less of a concern as machines with lots of memory will (or should) use
64-bit kernels. Combinations of 32-bit hardware and 64-bit hardware are
rare. Machines that do use highmem should have relatively low highmem:lowmem
ratios than we worried about in the past.
Conceptually, moving to node LRUs should be easier to understand. The
page allocator plays fewer tricks to game reclaim and reclaim behaves
similarly on all nodes.
The series has been tested on a 16 core UMA machine and a 2-socket 48
core NUMA machine. The UMA results are presented in most cases as the NUMA
machine behaved similarly.
pagealloc
---------
This is a microbenchmark that shows the benefit of removing the fair zone
allocation policy. It was tested uip to order-4 but only orders 0 and 1 are
shown as the other orders were comparable.
4.7.0-rc4 4.7.0-rc4
mmotm-20160623 nodelru-v9
Min total-odr0-1 490.00 ( 0.00%) 457.00 ( 6.73%)
Min total-odr0-2 347.00 ( 0.00%) 329.00 ( 5.19%)
Min total-odr0-4 288.00 ( 0.00%) 273.00 ( 5.21%)
Min total-odr0-8 251.00 ( 0.00%) 239.00 ( 4.78%)
Min total-odr0-16 234.00 ( 0.00%) 222.00 ( 5.13%)
Min total-odr0-32 223.00 ( 0.00%) 211.00 ( 5.38%)
Min total-odr0-64 217.00 ( 0.00%) 208.00 ( 4.15%)
Min total-odr0-128 214.00 ( 0.00%) 204.00 ( 4.67%)
Min total-odr0-256 250.00 ( 0.00%) 230.00 ( 8.00%)
Min total-odr0-512 271.00 ( 0.00%) 269.00 ( 0.74%)
Min total-odr0-1024 291.00 ( 0.00%) 282.00 ( 3.09%)
Min total-odr0-2048 303.00 ( 0.00%) 296.00 ( 2.31%)
Min total-odr0-4096 311.00 ( 0.00%) 309.00 ( 0.64%)
Min total-odr0-8192 316.00 ( 0.00%) 314.00 ( 0.63%)
Min total-odr0-16384 317.00 ( 0.00%) 315.00 ( 0.63%)
Min total-odr1-1 742.00 ( 0.00%) 712.00 ( 4.04%)
Min total-odr1-2 562.00 ( 0.00%) 530.00 ( 5.69%)
Min total-odr1-4 457.00 ( 0.00%) 433.00 ( 5.25%)
Min total-odr1-8 411.00 ( 0.00%) 381.00 ( 7.30%)
Min total-odr1-16 381.00 ( 0.00%) 356.00 ( 6.56%)
Min total-odr1-32 372.00 ( 0.00%) 346.00 ( 6.99%)
Min total-odr1-64 372.00 ( 0.00%) 343.00 ( 7.80%)
Min total-odr1-128 375.00 ( 0.00%) 351.00 ( 6.40%)
Min total-odr1-256 379.00 ( 0.00%) 351.00 ( 7.39%)
Min total-odr1-512 385.00 ( 0.00%) 355.00 ( 7.79%)
Min total-odr1-1024 386.00 ( 0.00%) 358.00 ( 7.25%)
Min total-odr1-2048 390.00 ( 0.00%) 362.00 ( 7.18%)
Min total-odr1-4096 390.00 ( 0.00%) 362.00 ( 7.18%)
Min total-odr1-8192 388.00 ( 0.00%) 363.00 ( 6.44%)
This shows a steady improvement throughout. The primary benefit is from
reduced system CPU usage which is obvious from the overall times;
4.7.0-rc4 4.7.0-rc4
mmotm-20160623nodelru-v8
User 189.19 191.80
System 2604.45 2533.56
Elapsed 2855.30 2786.39
The vmstats also showed that the fair zone allocation policy was definitely
removed as can be seen here;
4.7.0-rc3 4.7.0-rc3
mmotm-20160623 nodelru-v8
DMA32 allocs 28794729769 0
Normal allocs 48432501431 77227309877
Movable allocs 0 0
tiobench on ext4
----------------
tiobench is a benchmark that artifically benefits if old pages remain resident
while new pages get reclaimed. The fair zone allocation policy mitigates this
problem so pages age fairly. While the benchmark has problems, it is important
that tiobench performance remains constant as it implies that page aging
problems that the fair zone allocation policy fixes are not re-introduced.
4.7.0-rc4 4.7.0-rc4
mmotm-20160623 nodelru-v9
Min PotentialReadSpeed 89.65 ( 0.00%) 90.21 ( 0.62%)
Min SeqRead-MB/sec-1 82.68 ( 0.00%) 82.01 ( -0.81%)
Min SeqRead-MB/sec-2 72.76 ( 0.00%) 72.07 ( -0.95%)
Min SeqRead-MB/sec-4 75.13 ( 0.00%) 74.92 ( -0.28%)
Min SeqRead-MB/sec-8 64.91 ( 0.00%) 65.19 ( 0.43%)
Min SeqRead-MB/sec-16 62.24 ( 0.00%) 62.22 ( -0.03%)
Min RandRead-MB/sec-1 0.88 ( 0.00%) 0.88 ( 0.00%)
Min RandRead-MB/sec-2 0.95 ( 0.00%) 0.92 ( -3.16%)
Min RandRead-MB/sec-4 1.43 ( 0.00%) 1.34 ( -6.29%)
Min RandRead-MB/sec-8 1.61 ( 0.00%) 1.60 ( -0.62%)
Min RandRead-MB/sec-16 1.80 ( 0.00%) 1.90 ( 5.56%)
Min SeqWrite-MB/sec-1 76.41 ( 0.00%) 76.85 ( 0.58%)
Min SeqWrite-MB/sec-2 74.11 ( 0.00%) 73.54 ( -0.77%)
Min SeqWrite-MB/sec-4 80.05 ( 0.00%) 80.13 ( 0.10%)
Min SeqWrite-MB/sec-8 72.88 ( 0.00%) 73.20 ( 0.44%)
Min SeqWrite-MB/sec-16 75.91 ( 0.00%) 76.44 ( 0.70%)
Min RandWrite-MB/sec-1 1.18 ( 0.00%) 1.14 ( -3.39%)
Min RandWrite-MB/sec-2 1.02 ( 0.00%) 1.03 ( 0.98%)
Min RandWrite-MB/sec-4 1.05 ( 0.00%) 0.98 ( -6.67%)
Min RandWrite-MB/sec-8 0.89 ( 0.00%) 0.92 ( 3.37%)
Min RandWrite-MB/sec-16 0.92 ( 0.00%) 0.93 ( 1.09%)
4.7.0-rc4 4.7.0-rc4
mmotm-20160623 approx-v9
User 645.72 525.90
System 403.85 331.75
Elapsed 6795.36 6783.67
This shows that the series has little or not impact on tiobench which is
desirable and a reduction in system CPU usage. It indicates that the fair
zone allocation policy was removed in a manner that didn't reintroduce
one class of page aging bug. There were only minor differences in overall
reclaim activity
4.7.0-rc4 4.7.0-rc4
mmotm-20160623nodelru-v8
Minor Faults 645838 647465
Major Faults 573 640
Swap Ins 0 0
Swap Outs 0 0
DMA allocs 0 0
DMA32 allocs 46041453 44190646
Normal allocs 78053072 79887245
Movable allocs 0 0
Allocation stalls 24 67
Stall zone DMA 0 0
Stall zone DMA32 0 0
Stall zone Normal 0 2
Stall zone HighMem 0 0
Stall zone Movable 0 65
Direct pages scanned 10969 30609
Kswapd pages scanned 93375144 93492094
Kswapd pages reclaimed 93372243 93489370
Direct pages reclaimed 10969 30609
Kswapd efficiency 99% 99%
Kswapd velocity 13741.015 13781.934
Direct efficiency 100% 100%
Direct velocity 1.614 4.512
Percentage direct scans 0% 0%
kswapd activity was roughly comparable. There were differences in direct
reclaim activity but negligible in the context of the overall workload
(velocity of 4 pages per second with the patches applied, 1.6 pages per
second in the baseline kernel).
pgbench read-only large configuration on ext4
---------------------------------------------
pgbench is a database benchmark that can be sensitive to page reclaim
decisions. This also checks if removing the fair zone allocation policy
is safe
pgbench Transactions
4.7.0-rc4 4.7.0-rc4
mmotm-20160623 nodelru-v8
Hmean 1 188.26 ( 0.00%) 189.78 ( 0.81%)
Hmean 5 330.66 ( 0.00%) 328.69 ( -0.59%)
Hmean 12 370.32 ( 0.00%) 380.72 ( 2.81%)
Hmean 21 368.89 ( 0.00%) 369.00 ( 0.03%)
Hmean 30 382.14 ( 0.00%) 360.89 ( -5.56%)
Hmean 32 428.87 ( 0.00%) 432.96 ( 0.95%)
Negligible differences again. As with tiobench, overall reclaim activity
was comparable.
bonnie++ on ext4
----------------
No interesting performance difference, negligible differences on reclaim
stats.
paralleldd on ext4
------------------
This workload uses varying numbers of dd instances to read large amounts of
data from disk.
4.7.0-rc3 4.7.0-rc3
mmotm-20160623 nodelru-v9
Amean Elapsd-1 186.04 ( 0.00%) 189.41 ( -1.82%)
Amean Elapsd-3 192.27 ( 0.00%) 191.38 ( 0.46%)
Amean Elapsd-5 185.21 ( 0.00%) 182.75 ( 1.33%)
Amean Elapsd-7 183.71 ( 0.00%) 182.11 ( 0.87%)
Amean Elapsd-12 180.96 ( 0.00%) 181.58 ( -0.35%)
Amean Elapsd-16 181.36 ( 0.00%) 183.72 ( -1.30%)
4.7.0-rc4 4.7.0-rc4
mmotm-20160623 nodelru-v9
User 1548.01 1552.44
System 8609.71 8515.08
Elapsed 3587.10 3594.54
There is little or no change in performance but some drop in system CPU usage.
4.7.0-rc3 4.7.0-rc3
mmotm-20160623 nodelru-v9
Minor Faults 362662 367360
Major Faults 1204 1143
Swap Ins 22 0
Swap Outs 2855 1029
DMA allocs 0 0
DMA32 allocs 31409797 28837521
Normal allocs 46611853 49231282
Movable allocs 0 0
Direct pages scanned 0 0
Kswapd pages scanned 40845270 40869088
Kswapd pages reclaimed 40830976 40855294
Direct pages reclaimed 0 0
Kswapd efficiency 99% 99%
Kswapd velocity 11386.711 11369.769
Direct efficiency 100% 100%
Direct velocity 0.000 0.000
Percentage direct scans 0% 0%
Page writes by reclaim 2855 1029
Page writes file 0 0
Page writes anon 2855 1029
Page reclaim immediate 771 1628
Sector Reads 293312636 293536360
Sector Writes 18213568 18186480
Page rescued immediate 0 0
Slabs scanned 128257 132747
Direct inode steals 181 56
Kswapd inode steals 59 1131
It basically shows that kswapd was active at roughly the same rate in
both kernels. There was also comparable slab scanning activity and direct
reclaim was avoided in both cases. There appears to be a large difference
in numbers of inodes reclaimed but the workload has few active inodes and
is likely a timing artifact.
stutter
-------
stutter simulates a simple workload. One part uses a lot of anonymous
memory, a second measures mmap latency and a third copies a large file.
The primary metric is checking for mmap latency.
stutter
4.7.0-rc4 4.7.0-rc4
mmotm-20160623 nodelru-v8
Min mmap 16.6283 ( 0.00%) 13.4258 ( 19.26%)
1st-qrtle mmap 54.7570 ( 0.00%) 34.9121 ( 36.24%)
2nd-qrtle mmap 57.3163 ( 0.00%) 46.1147 ( 19.54%)
3rd-qrtle mmap 58.9976 ( 0.00%) 47.1882 ( 20.02%)
Max-90% mmap 59.7433 ( 0.00%) 47.4453 ( 20.58%)
Max-93% mmap 60.1298 ( 0.00%) 47.6037 ( 20.83%)
Max-95% mmap 73.4112 ( 0.00%) 82.8719 (-12.89%)
Max-99% mmap 92.8542 ( 0.00%) 88.8870 ( 4.27%)
Max mmap 1440.6569 ( 0.00%) 121.4201 ( 91.57%)
Mean mmap 59.3493 ( 0.00%) 42.2991 ( 28.73%)
Best99%Mean mmap 57.2121 ( 0.00%) 41.8207 ( 26.90%)
Best95%Mean mmap 55.9113 ( 0.00%) 39.9620 ( 28.53%)
Best90%Mean mmap 55.6199 ( 0.00%) 39.3124 ( 29.32%)
Best50%Mean mmap 53.2183 ( 0.00%) 33.1307 ( 37.75%)
Best10%Mean mmap 45.9842 ( 0.00%) 20.4040 ( 55.63%)
Best5%Mean mmap 43.2256 ( 0.00%) 17.9654 ( 58.44%)
Best1%Mean mmap 32.9388 ( 0.00%) 16.6875 ( 49.34%)
This shows a number of improvements with the worst-case outlier greatly
improved.
Some of the vmstats are interesting
4.7.0-rc4 4.7.0-rc4
mmotm-20160623nodelru-v8
Swap Ins 163 502
Swap Outs 0 0
DMA allocs 0 0
DMA32 allocs 618719206 1381662383
Normal allocs 891235743 564138421
Movable allocs 0 0
Allocation stalls 2603 1
Direct pages scanned 216787 2
Kswapd pages scanned 50719775 41778378
Kswapd pages reclaimed 41541765 41777639
Direct pages reclaimed 209159 0
Kswapd efficiency 81% 99%
Kswapd velocity 16859.554 14329.059
Direct efficiency 96% 0%
Direct velocity 72.061 0.001
Percentage direct scans 0% 0%
Page writes by reclaim 6215049 0
Page writes file 6215049 0
Page writes anon 0 0
Page reclaim immediate 70673 90
Sector Reads 81940800 81680456
Sector Writes 100158984 98816036
Page rescued immediate 0 0
Slabs scanned 1366954 22683
While this is not guaranteed in all cases, this particular test showed
a large reduction in direct reclaim activity. It's also worth noting
that no page writes were issued from reclaim context.
This series is not without its hazards. There are at least three areas
that I'm concerned with even though I could not reproduce any problems in
that area.
1. Reclaim/compaction is going to be affected because the amount of reclaim is
no longer targetted at a specific zone. Compaction works on a per-zone basis
so there is no guarantee that reclaiming a few THP's worth page pages will
have a positive impact on compaction success rates.
2. The Slab/LRU reclaim ratio is affected because the frequency the shrinkers
are called is now different. This may or may not be a problem but if it
is, it'll be because shrinkers are not called enough and some balancing
is required.
3. The anon/file reclaim ratio may be affected. Pages about to be dirtied are
distributed between zones and the fair zone allocation policy used to do
something very similar for anon. The distribution is now different but not
necessarily in any way that matters but it's still worth bearing in mind.
VM statistic counters for reclaim decisions are zone-based. If the kernel
is to reclaim on a per-node basis then we need to track per-node
statistics but there is no infrastructure for that. The most notable
change is that the old node_page_state is renamed to
sum_zone_node_page_state. The new node_page_state takes a pglist_data and
uses per-node stats but none exist yet. There is some renaming such as
vm_stat to vm_zone_stat and the addition of vm_node_stat and the renaming
of mod_state to mod_zone_state. Otherwise, this is mostly a mechanical
patch with no functional change. There is a lot of similarity between the
node and zone helpers which is unfortunate but there was no obvious way of
reusing the code and maintaining type safety.
Link: http://lkml.kernel.org/r/1467970510-21195-2-git-send-email-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
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Kirill A. Shutemov
|
65c453778a |
mm, rmap: account shmem thp pages
Let's add ShmemHugePages and ShmemPmdMapped fields into meminfo and smaps. It indicates how many times we allocate and map shmem THP. NR_ANON_TRANSPARENT_HUGEPAGES is renamed to NR_ANON_THPS. Link: http://lkml.kernel.org/r/1466021202-61880-27-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Kirill A. Shutemov
|
95ecedcd6a |
thp, vmstats: add counters for huge file pages
THP_FILE_ALLOC: how many times huge page was allocated and put page cache. THP_FILE_MAPPED: how many times file huge page was mapped. Link: http://lkml.kernel.org/r/1466021202-61880-13-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Minchan Kim
|
91537fee00 |
mm: add NR_ZSMALLOC to vmstat
zram is very popular for some of the embedded world (e.g., TV, mobile phones). On those system, zsmalloc's consumed memory size is never trivial (one of example from real product system, total memory: 800M, zsmalloc consumed: 150M), so we have used this out of tree patch to monitor system memory behavior via /proc/vmstat. With zsmalloc in vmstat, it helps in tracking down system behavior due to memory usage. [minchan@kernel.org: zsmalloc: follow up zsmalloc vmstat] Link: http://lkml.kernel.org/r/20160607091737.GC23435@bbox [akpm@linux-foundation.org: fix build with CONFIG_ZSMALLOC=m] Link: http://lkml.kernel.org/r/1464919731-13255-1-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Sangseok Lee <sangseok.lee@lge.com> Cc: Chanho Min <chanho.min@lge.com> Cc: Chan Gyun Jeong <chan.jeong@lge.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Yang Shi
|
f86e427197 |
mm: check the return value of lookup_page_ext for all call sites
Per the discussion with Joonsoo Kim [1], we need check the return value of lookup_page_ext() for all call sites since it might return NULL in some cases, although it is unlikely, i.e. memory hotplug. Tested with ltp with "page_owner=0". [1] http://lkml.kernel.org/r/20160519002809.GA10245@js1304-P5Q-DELUXE [akpm@linux-foundation.org: fix build-breaking typos] [arnd@arndb.de: fix build problems from lookup_page_ext] Link: http://lkml.kernel.org/r/6285269.2CksypHdYp@wuerfel [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1464023768-31025-1-git-send-email-yang.shi@linaro.org Signed-off-by: Yang Shi <yang.shi@linaro.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Christoph Lameter
|
7b8da4c7f0 |
vmstat: get rid of the ugly cpu_stat_off variable
The cpu_stat_off variable is unecessary since we can check if a workqueue request is pending otherwise. Removal of cpu_stat_off makes it pretty easy for the vmstat shepherd to ensure that the proper things happen. Removing the state also removes all races related to it. Should a workqueue not be scheduled as needed for vmstat_update then the shepherd will notice and schedule it as needed. Should a workqueue be unecessarily scheduled then the vmstat updater will disable it. [akpm@linux-foundation.org: fix indentation, per Michal] Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1605061306460.17934@east.gentwo.org Signed-off-by: Christoph Lameter <cl@linux.com> Cc: Tejun Heo <htejun@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
0b423ca22f |
mm, page_alloc: inline pageblock lookup in page free fast paths
The function call overhead of get_pfnblock_flags_mask() is measurable in the page free paths. This patch uses an inlined version that is faster. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
060e74173f |
mm, page_alloc: inline zone_statistics
zone_statistics has one call-site but it's a public function. Make it
static and inline.
The performance difference on a page allocator microbenchmark is;
4.6.0-rc2 4.6.0-rc2
statbranch-v1r20 statinline-v1r20
Min alloc-odr0-1 419.00 ( 0.00%) 412.00 ( 1.67%)
Min alloc-odr0-2 305.00 ( 0.00%) 301.00 ( 1.31%)
Min alloc-odr0-4 250.00 ( 0.00%) 247.00 ( 1.20%)
Min alloc-odr0-8 219.00 ( 0.00%) 215.00 ( 1.83%)
Min alloc-odr0-16 203.00 ( 0.00%) 199.00 ( 1.97%)
Min alloc-odr0-32 195.00 ( 0.00%) 191.00 ( 2.05%)
Min alloc-odr0-64 191.00 ( 0.00%) 187.00 ( 2.09%)
Min alloc-odr0-128 189.00 ( 0.00%) 185.00 ( 2.12%)
Min alloc-odr0-256 198.00 ( 0.00%) 193.00 ( 2.53%)
Min alloc-odr0-512 210.00 ( 0.00%) 207.00 ( 1.43%)
Min alloc-odr0-1024 216.00 ( 0.00%) 213.00 ( 1.39%)
Min alloc-odr0-2048 221.00 ( 0.00%) 220.00 ( 0.45%)
Min alloc-odr0-4096 227.00 ( 0.00%) 226.00 ( 0.44%)
Min alloc-odr0-8192 232.00 ( 0.00%) 229.00 ( 1.29%)
Min alloc-odr0-16384 232.00 ( 0.00%) 229.00 ( 1.29%)
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Mel Gorman
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b9f00e147f |
mm, page_alloc: reduce branches in zone_statistics
zone_statistics has more branches than it really needs to take an
unlikely GFP flag into account. Reduce the number and annotate the
unlikely flag.
The performance difference on a page allocator microbenchmark is;
4.6.0-rc2 4.6.0-rc2
nocompound-v1r10 statbranch-v1r10
Min alloc-odr0-1 417.00 ( 0.00%) 419.00 ( -0.48%)
Min alloc-odr0-2 308.00 ( 0.00%) 305.00 ( 0.97%)
Min alloc-odr0-4 253.00 ( 0.00%) 250.00 ( 1.19%)
Min alloc-odr0-8 221.00 ( 0.00%) 219.00 ( 0.90%)
Min alloc-odr0-16 205.00 ( 0.00%) 203.00 ( 0.98%)
Min alloc-odr0-32 199.00 ( 0.00%) 195.00 ( 2.01%)
Min alloc-odr0-64 193.00 ( 0.00%) 191.00 ( 1.04%)
Min alloc-odr0-128 191.00 ( 0.00%) 189.00 ( 1.05%)
Min alloc-odr0-256 200.00 ( 0.00%) 198.00 ( 1.00%)
Min alloc-odr0-512 212.00 ( 0.00%) 210.00 ( 0.94%)
Min alloc-odr0-1024 219.00 ( 0.00%) 216.00 ( 1.37%)
Min alloc-odr0-2048 225.00 ( 0.00%) 221.00 ( 1.78%)
Min alloc-odr0-4096 231.00 ( 0.00%) 227.00 ( 1.73%)
Min alloc-odr0-8192 234.00 ( 0.00%) 232.00 ( 0.85%)
Min alloc-odr0-16384 234.00 ( 0.00%) 232.00 ( 0.85%)
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Hugh Dickins
|
52b6f46bc1 |
mm: /proc/sys/vm/stat_refresh to force vmstat update
Provide /proc/sys/vm/stat_refresh to force an immediate update of per-cpu into global vmstats: useful to avoid a sleep(2) or whatever before checking counts when testing. Originally added to work around a bug which left counts stranded indefinitely on a cpu going idle (an inaccuracy magnified when small below-batch numbers represent "huge" amounts of memory), but I believe that bug is now fixed: nonetheless, this is still a useful knob. Its schedule_on_each_cpu() is probably too expensive just to fold into reading /proc/meminfo itself: give this mode 0600 to prevent abuse. Allow a write or a read to do the same: nothing to read, but "grep -h Shmem /proc/sys/vm/stat_refresh /proc/meminfo" is convenient. Oh, and since global_page_state() itself is careful to disguise any underflow as 0, hack in an "Invalid argument" and pr_warn() if a counter is negative after the refresh - this helped to fix a misaccounting of NR_ISOLATED_FILE in my migration code. But on recent kernels, I find that NR_ALLOC_BATCH and NR_PAGES_SCANNED often go negative some of the time. I have not yet worked out why, but have no evidence that it's actually harmful. Punt for the moment by just ignoring the anomaly on those. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Yang Shi <yang.shi@linaro.org> Cc: Ning Qu <quning@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Joonsoo Kim
|
e87d59f7a2 |
mm/vmstat: make node_page_state() handles all zones by itself
node_page_state() manually adds statistics per each zone and returns total value for all zones. Whenever we add a new zone, we need to consider this function and it's really troublesome. Make it handle all zones by itself. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Laura Abbott <lauraa@codeaurora.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Joonsoo Kim
|
a91c43c731 |
mm/vmstat: add zone range overlapping check
There is a system thats node's pfns are overlapped as follows: -----pfn--------> N0 N1 N2 N0 N1 N2 Therefore, we need to care this overlapping when iterating pfn range. There are two places in vmstat.c that iterates pfn range and they don't consider this overlapping. Add it. Without this patch, above system could over count pageblock number on a zone. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Laura Abbott <lauraa@codeaurora.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Kirill A. Shutemov
|
f9719a03de |
thp, vmstats: count deferred split events
Count how many times we put a THP in split queue. Currently, it happens on partial unmap of a THP. Rapidly growing value can indicate that an application behaves unfriendly wrt THP: often fault in huge page and then unmap part of it. This leads to unnecessary memory fragmentation and the application may require tuning. The event also can help with debugging kernel [mis-]behaviour. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vlastimil Babka
|
698b1b3064 |
mm, compaction: introduce kcompactd
Memory compaction can be currently performed in several contexts: - kswapd balancing a zone after a high-order allocation failure - direct compaction to satisfy a high-order allocation, including THP page fault attemps - khugepaged trying to collapse a hugepage - manually from /proc The purpose of compaction is two-fold. The obvious purpose is to satisfy a (pending or future) high-order allocation, and is easy to evaluate. The other purpose is to keep overal memory fragmentation low and help the anti-fragmentation mechanism. The success wrt the latter purpose is more The current situation wrt the purposes has a few drawbacks: - compaction is invoked only when a high-order page or hugepage is not available (or manually). This might be too late for the purposes of keeping memory fragmentation low. - direct compaction increases latency of allocations. Again, it would be better if compaction was performed asynchronously to keep fragmentation low, before the allocation itself comes. - (a special case of the previous) the cost of compaction during THP page faults can easily offset the benefits of THP. - kswapd compaction appears to be complex, fragile and not working in some scenarios. It could also end up compacting for a high-order allocation request when it should be reclaiming memory for a later order-0 request. To improve the situation, we should be able to benefit from an equivalent of kswapd, but for compaction - i.e. a background thread which responds to fragmentation and the need for high-order allocations (including hugepages) somewhat proactively. One possibility is to extend the responsibilities of kswapd, which could however complicate its design too much. It should be better to let kswapd handle reclaim, as order-0 allocations are often more critical than high-order ones. Another possibility is to extend khugepaged, but this kthread is a single instance and tied to THP configs. This patch goes with the option of a new set of per-node kthreads called kcompactd, and lays the foundations, without introducing any new tunables. The lifecycle mimics kswapd kthreads, including the memory hotplug hooks. For compaction, kcompactd uses the standard compaction_suitable() and ompact_finished() criteria and the deferred compaction functionality. Unlike direct compaction, it uses only sync compaction, as there's no allocation latency to minimize. This patch doesn't yet add a call to wakeup_kcompactd. The kswapd compact/reclaim loop for high-order pages will be replaced by waking up kcompactd in the next patch with the description of what's wrong with the old approach. Waking up of the kcompactd threads is also tied to kswapd activity and follows these rules: - we don't want to affect any fastpaths, so wake up kcompactd only from the slowpath, as it's done for kswapd - if kswapd is doing reclaim, it's more important than compaction, so don't invoke kcompactd until kswapd goes to sleep - the target order used for kswapd is passed to kcompactd Future possible future uses for kcompactd include the ability to wake up kcompactd on demand in special situations, such as when hugepages are not available (currently not done due to __GFP_NO_KSWAPD) or when a fragmentation event (i.e. __rmqueue_fallback()) occurs. It's also possible to perform periodic compaction with kcompactd. [arnd@arndb.de: fix build errors with kcompactd] [paul.gortmaker@windriver.com: don't use modular references for non modular code] Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vlastimil Babka
|
7dd80b8af0 |
mm, page_owner: convert page_owner_inited to static key
CONFIG_PAGE_OWNER attempts to impose negligible runtime overhead when enabled during compilation, but not actually enabled during runtime by boot param page_owner=on. This overhead can be further reduced using the static key mechanism, which this patch does. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vlastimil Babka
|
60f30350fd |
mm, page_owner: print migratetype of page and pageblock, symbolic flags
The information in /sys/kernel/debug/page_owner includes the migratetype of the pageblock the page belongs to. This is also checked against the page's migratetype (as declared by gfp_flags during its allocation), and the page is reported as Fallback if its migratetype differs from the pageblock's one. t This is somewhat misleading because in fact fallback allocation is not the only reason why these two can differ. It also doesn't direcly provide the page's migratetype, although it's possible to derive that from the gfp_flags. It's arguably better to print both page and pageblock's migratetype and leave the interpretation to the consumer than to suggest fallback allocation as the only possible reason. While at it, we can print the migratetypes as string the same way as /proc/pagetypeinfo does, as some of the numeric values depend on kernel configuration. For that, this patch moves the migratetype_names array from #ifdef CONFIG_PROC_FS part of mm/vmstat.c to mm/page_alloc.c and exports it. With the new format strings for flags, we can now also provide symbolic page and gfp flags in the /sys/kernel/debug/page_owner file. This replaces the positional printing of page flags as single letters, which might have looked nicer, but was limited to a subset of flags, and required the user to remember the letters. Example page_owner entry after the patch: Page allocated via order 0, mask 0x24213ca(GFP_HIGHUSER_MOVABLE|__GFP_COLD|__GFP_NOWARN|__GFP_NORETRY) PFN 520 type Movable Block 1 type Movable Flags 0xfffff8001006c(referenced|uptodate|lru|active|mappedtodisk) [<ffffffff811682c4>] __alloc_pages_nodemask+0x134/0x230 [<ffffffff811b4058>] alloc_pages_current+0x88/0x120 [<ffffffff8115e386>] __page_cache_alloc+0xe6/0x120 [<ffffffff8116ba6c>] __do_page_cache_readahead+0xdc/0x240 [<ffffffff8116bd05>] ondemand_readahead+0x135/0x260 [<ffffffff8116bfb1>] page_cache_sync_readahead+0x31/0x50 [<ffffffff81160523>] generic_file_read_iter+0x453/0x760 [<ffffffff811e0d57>] __vfs_read+0xa7/0xd0 Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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ccde8bd401 |
vmstat: make vmstat_update deferrable
Commit
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Michal Hocko
|
f01f17d370 |
mm, vmstat: make quiet_vmstat lighter
Mike has reported a considerable overhead of refresh_cpu_vm_stats from
the idle entry during pipe test:
12.89% [kernel] [k] refresh_cpu_vm_stats.isra.12
4.75% [kernel] [k] __schedule
4.70% [kernel] [k] mutex_unlock
3.14% [kernel] [k] __switch_to
This is caused by commit
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Christoph Lameter
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587198ba52 |
vmstat: Remove BUG_ON from vmstat_update
If we detect that there is nothing to do just set the flag and do not
check if it was already set before. Races really do not matter. If the
flag is set by any code then the shepherd will start dealing with the
situation and reenable the vmstat workers when necessary again.
Since commit
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Minchan Kim
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854e9ed09d |
mm: support madvise(MADV_FREE)
Linux doesn't have an ability to free pages lazy while other OS already have been supported that named by madvise(MADV_FREE). The gain is clear that kernel can discard freed pages rather than swapping out or OOM if memory pressure happens. Without memory pressure, freed pages would be reused by userspace without another additional overhead(ex, page fault + allocation + zeroing). Jason Evans said: : Facebook has been using MAP_UNINITIALIZED : (https://lkml.org/lkml/2012/1/18/308) in some of its applications for : several years, but there are operational costs to maintaining this : out-of-tree in our kernel and in jemalloc, and we are anxious to retire it : in favor of MADV_FREE. When we first enabled MAP_UNINITIALIZED it : increased throughput for much of our workload by ~5%, and although the : benefit has decreased using newer hardware and kernels, there is still : enough benefit that we cannot reasonably retire it without a replacement. : : Aside from Facebook operations, there are numerous broadly used : applications that would benefit from MADV_FREE. The ones that immediately : come to mind are redis, varnish, and MariaDB. I don't have much insight : into Android internals and development process, but I would hope to see : MADV_FREE support eventually end up there as well to benefit applications : linked with the integrated jemalloc. : : jemalloc will use MADV_FREE once it becomes available in the Linux kernel. : In fact, jemalloc already uses MADV_FREE or equivalent everywhere it's : available: *BSD, OS X, Windows, and Solaris -- every platform except Linux : (and AIX, but I'm not sure it even compiles on AIX). The lack of : MADV_FREE on Linux forced me down a long series of increasingly : sophisticated heuristics for madvise() volume reduction, and even so this : remains a common performance issue for people using jemalloc on Linux. : Please integrate MADV_FREE; many people will benefit substantially. How it works: When madvise syscall is called, VM clears dirty bit of ptes of the range. If memory pressure happens, VM checks dirty bit of page table and if it found still "clean", it means it's a "lazyfree pages" so VM could discard the page instead of swapping out. Once there was store operation for the page before VM peek a page to reclaim, dirty bit is set so VM can swap out the page instead of discarding. One thing we should notice is that basically, MADV_FREE relies on dirty bit in page table entry to decide whether VM allows to discard the page or not. IOW, if page table entry includes marked dirty bit, VM shouldn't discard the page. However, as a example, if swap-in by read fault happens, page table entry doesn't have dirty bit so MADV_FREE could discard the page wrongly. For avoiding the problem, MADV_FREE did more checks with PageDirty and PageSwapCache. It worked out because swapped-in page lives on swap cache and since it is evicted from the swap cache, the page has PG_dirty flag. So both page flags check effectively prevent wrong discarding by MADV_FREE. However, a problem in above logic is that swapped-in page has PG_dirty still after they are removed from swap cache so VM cannot consider the page as freeable any more even if madvise_free is called in future. Look at below example for detail. ptr = malloc(); memset(ptr); .. .. .. heavy memory pressure so all of pages are swapped out .. .. var = *ptr; -> a page swapped-in and could be removed from swapcache. Then, page table doesn't mark dirty bit and page descriptor includes PG_dirty .. .. madvise_free(ptr); -> It doesn't clear PG_dirty of the page. .. .. .. .. heavy memory pressure again. .. In this time, VM cannot discard the page because the page .. has *PG_dirty* To solve the problem, this patch clears PG_dirty if only the page is owned exclusively by current process when madvise is called because PG_dirty represents ptes's dirtiness in several processes so we could clear it only if we own it exclusively. Firstly, heavy users would be general allocators(ex, jemalloc, tcmalloc and hope glibc supports it) and jemalloc/tcmalloc already have supported the feature for other OS(ex, FreeBSD) barrios@blaptop:~/benchmark/ebizzy$ lscpu Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 12 On-line CPU(s) list: 0-11 Thread(s) per core: 1 Core(s) per socket: 1 Socket(s): 12 NUMA node(s): 1 Vendor ID: GenuineIntel CPU family: 6 Model: 2 Stepping: 3 CPU MHz: 3200.185 BogoMIPS: 6400.53 Virtualization: VT-x Hypervisor vendor: KVM Virtualization type: full L1d cache: 32K L1i cache: 32K L2 cache: 4096K NUMA node0 CPU(s): 0-11 ebizzy benchmark(./ebizzy -S 10 -n 512) Higher avg is better. vanilla-jemalloc MADV_free-jemalloc 1 thread records: 10 records: 10 avg: 2961.90 avg: 12069.70 std: 71.96(2.43%) std: 186.68(1.55%) max: 3070.00 max: 12385.00 min: 2796.00 min: 11746.00 2 thread records: 10 records: 10 avg: 5020.00 avg: 17827.00 std: 264.87(5.28%) std: 358.52(2.01%) max: 5244.00 max: 18760.00 min: 4251.00 min: 17382.00 4 thread records: 10 records: 10 avg: 8988.80 avg: 27930.80 std: 1175.33(13.08%) std: 3317.33(11.88%) max: 9508.00 max: 30879.00 min: 5477.00 min: 21024.00 8 thread records: 10 records: 10 avg: 13036.50 avg: 33739.40 std: 170.67(1.31%) std: 5146.22(15.25%) max: 13371.00 max: 40572.00 min: 12785.00 min: 24088.00 16 thread records: 10 records: 10 avg: 11092.40 avg: 31424.20 std: 710.60(6.41%) std: 3763.89(11.98%) max: 12446.00 max: 36635.00 min: 9949.00 min: 25669.00 32 thread records: 10 records: 10 avg: 11067.00 avg: 34495.80 std: 971.06(8.77%) std: 2721.36(7.89%) max: 12010.00 max: 38598.00 min: 9002.00 min: 30636.00 In summary, MADV_FREE is about much faster than MADV_DONTNEED. This patch (of 12): Add core MADV_FREE implementation. [akpm@linux-foundation.org: small cleanups] Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Mika Penttil <mika.penttila@nextfour.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Jason Evans <je@fb.com> Cc: Daniel Micay <danielmicay@gmail.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Shaohua Li <shli@kernel.org> Cc: <yalin.wang2010@gmail.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: "Shaohua Li" <shli@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen Gang <gang.chen.5i5j@gmail.com> Cc: Chris Zankel <chris@zankel.net> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: David S. Miller <davem@davemloft.net> Cc: Helge Deller <deller@gmx.de> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Roland Dreier <roland@kernel.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Shaohua Li <shli@kernel.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Kirill A. Shutemov
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122afea962 |
mm, vmstats: new THP splitting event
The patch replaces THP_SPLIT with tree events: THP_SPLIT_PAGE, THP_SPLIT_PAGE_FAILED and THP_SPLIT_PMD. It reflects the fact that we are going to be able split PMD without the compound page and that split_huge_page() can fail. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Christoph Lameter <cl@linux.com> Tested-by: Sasha Levin <sasha.levin@oracle.com> Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Jerome Marchand <jmarchan@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Christoph Lameter
|
0eb77e9880 |
vmstat: make vmstat_updater deferrable again and shut down on idle
Currently the vmstat updater is not deferrable as a result of commit |
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Michal Hocko
|
751e5f5c75 |
vmstat: allocate vmstat_wq before it is used
kernel test robot has reported the following crash:
BUG: unable to handle kernel NULL pointer dereference at 00000100
IP: [<c1074df6>] __queue_work+0x26/0x390
*pdpt = 0000000000000000 *pde = f000ff53f000ff53 *pde = f000ff53f000ff53
Oops: 0000 [#1] PREEMPT PREEMPT SMP SMP
CPU: 0 PID: 24 Comm: kworker/0:1 Not tainted 4.4.0-rc4-00139-g373ccbe #1
Workqueue: events vmstat_shepherd
task: cb684600 ti: cb7ba000 task.ti: cb7ba000
EIP: 0060:[<c1074df6>] EFLAGS: 00010046 CPU: 0
EIP is at __queue_work+0x26/0x390
EAX: 00000046 EBX: cbb37800 ECX: cbb37800 EDX: 00000000
ESI: 00000000 EDI: 00000000 EBP: cb7bbe68 ESP: cb7bbe38
DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
CR0: 8005003b CR2: 00000100 CR3: 01fd5000 CR4: 000006b0
Stack:
Call Trace:
__queue_delayed_work+0xa1/0x160
queue_delayed_work_on+0x36/0x60
vmstat_shepherd+0xad/0xf0
process_one_work+0x1aa/0x4c0
worker_thread+0x41/0x440
kthread+0xb0/0xd0
ret_from_kernel_thread+0x21/0x40
The reason is that start_shepherd_timer schedules the shepherd work item
which uses vmstat_wq (vmstat_shepherd) before setup_vmstat allocates
that workqueue so if the further initialization takes more than HZ we
might end up scheduling on a NULL vmstat_wq. This is really unlikely
but not impossible.
Fixes:
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Heiko Carstens
|
6cdb18ad98 |
mm/vmstat: fix overflow in mod_zone_page_state()
mod_zone_page_state() takes a "delta" integer argument. delta contains
the number of pages that should be added or subtracted from a struct
zone's vm_stat field.
If a zone is larger than 8TB this will cause overflows. E.g. for a
zone with a size slightly larger than 8TB the line
mod_zone_page_state(zone, NR_ALLOC_BATCH, zone->managed_pages);
in mm/page_alloc.c:free_area_init_core() will result in a negative
result for the NR_ALLOC_BATCH entry within the zone's vm_stat, since 8TB
contain 0x8xxxxxxx pages which will be sign extended to a negative
value.
Fix this by changing the delta argument to long type.
This could fix an early boot problem seen on s390, where we have a 9TB
system with only one node. ZONE_DMA contains 2GB and ZONE_NORMAL the
rest. The system is trying to allocate a GFP_DMA page but ZONE_DMA is
completely empty, so it tries to reclaim pages in an endless loop.
This was seen on a heavily patched 3.10 kernel. One possible
explaination seem to be the overflows caused by mod_zone_page_state().
Unfortunately I did not have the chance to verify that this patch
actually fixes the problem, since I don't have access to the system
right now. However the overflow problem does exist anyway.
Given the description that a system with slightly less than 8TB does
work, this seems to be a candidate for the observed problem.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Michal Hocko
|
373ccbe592 |
mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress
Tetsuo Handa has reported that the system might basically livelock in
OOM condition without triggering the OOM killer.
The issue is caused by internal dependency of the direct reclaim on
vmstat counter updates (via zone_reclaimable) which are performed from
the workqueue context. If all the current workers get assigned to an
allocation request, though, they will be looping inside the allocator
trying to reclaim memory but zone_reclaimable can see stalled numbers so
it will consider a zone reclaimable even though it has been scanned way
too much. WQ concurrency logic will not consider this situation as a
congested workqueue because it relies that worker would have to sleep in
such a situation. This also means that it doesn't try to spawn new
workers or invoke the rescuer thread if the one is assigned to the
queue.
In order to fix this issue we need to do two things. First we have to
let wq concurrency code know that we are in trouble so we have to do a
short sleep. In order to prevent from issues handled by
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Vlastimil Babka
|
475a2f905d |
mm: fix swapped Movable and Reclaimable in /proc/pagetypeinfo
Commit |
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Mel Gorman
|
0aaa29a56e |
mm, page_alloc: reserve pageblocks for high-order atomic allocations on demand
High-order watermark checking exists for two reasons -- kswapd high-order awareness and protection for high-order atomic requests. Historically the kernel depended on MIGRATE_RESERVE to preserve min_free_kbytes as high-order free pages for as long as possible. This patch introduces MIGRATE_HIGHATOMIC that reserves pageblocks for high-order atomic allocations on demand and avoids using those blocks for order-0 allocations. This is more flexible and reliable than MIGRATE_RESERVE was. A MIGRATE_HIGHORDER pageblock is created when an atomic high-order allocation request steals a pageblock but limits the total number to 1% of the zone. Callers that speculatively abuse atomic allocations for long-lived high-order allocations to access the reserve will quickly fail. Note that SLUB is currently not such an abuser as it reclaims at least once. It is possible that the pageblock stolen has few suitable high-order pages and will need to steal again in the near future but there would need to be strong justification to search all pageblocks for an ideal candidate. The pageblocks are unreserved if an allocation fails after a direct reclaim attempt. The watermark checks account for the reserved pageblocks when the allocation request is not a high-order atomic allocation. The reserved pageblocks can not be used for order-0 allocations. This may allow temporary wastage until a failed reclaim reassigns the pageblock. This is deliberate as the intent of the reservation is to satisfy a limited number of atomic high-order short-lived requests if the system requires them. The stutter benchmark was used to evaluate this but while it was running there was a systemtap script that randomly allocated between 1 high-order page and 12.5% of memory's worth of order-3 pages using GFP_ATOMIC. This is much larger than the potential reserve and it does not attempt to be realistic. It is intended to stress random high-order allocations from an unknown source, show that there is a reduction in failures without introducing an anomaly where atomic allocations are more reliable than regular allocations. The amount of memory reserved varied throughout the workload as reserves were created and reclaimed under memory pressure. The allocation failures once the workload warmed up were as follows; 4.2-rc5-vanilla 70% 4.2-rc5-atomic-reserve 56% The failure rate was also measured while building multiple kernels. The failure rate was 14% but is 6% with this patch applied. Overall, this is a small reduction but the reserves are small relative to the number of allocation requests. In early versions of the patch, the failure rate reduced by a much larger amount but that required much larger reserves and perversely made atomic allocations seem more reliable than regular allocations. [yalin.wang2010@gmail.com: fix redundant check and a memory leak] Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: yalin wang <yalin.wang2010@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
974a786e63 |
mm, page_alloc: remove MIGRATE_RESERVE
MIGRATE_RESERVE preserves an old property of the buddy allocator that existed prior to fragmentation avoidance -- min_free_kbytes worth of pages tended to remain contiguous until the only alternative was to fail the allocation. At the time it was discovered that high-order atomic allocations relied on this property so MIGRATE_RESERVE was introduced. A later patch will introduce an alternative MIGRATE_HIGHATOMIC so this patch deletes MIGRATE_RESERVE and supporting code so it'll be easier to review. Note that this patch in isolation may look like a false regression if someone was bisecting high-order atomic allocation failures. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrew Morton
|
c2d42c16ad |
mm/vmstat.c: uninline node_page_state()
With x86_64 (config http://ozlabs.org/~akpm/config-akpm2.txt) and old gcc (4.4.4), drivers/base/node.c:node_read_meminfo() is using 2344 bytes of stack. Uninlining node_page_state() reduces this to 440 bytes. The stack consumption issue is fixed by newer gcc (4.8.4) however with that compiler this patch reduces the node.o text size from 7314 bytes to 4578. Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds
|
176bed1de5 |
vmstat: explicitly schedule per-cpu work on the CPU we need it to run on
The vmstat code uses "schedule_delayed_work_on()" to do the initial
startup of the delayed work on the right CPU, but then once it was
started it would use the non-cpu-specific "schedule_delayed_work()" to
re-schedule it on that CPU.
That just happened to schedule it on the same CPU historically (well, in
almost all situations), but the code _requires_ this work to be per-cpu,
and should say so explicitly rather than depend on the non-cpu-specific
scheduling to schedule on the current CPU.
The timer code is being changed to not be as single-minded in always
running things on the calling CPU.
See also commit
|
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|
Christoph Lameter
|
57c2e36b6f |
vmstat: Reduce time interval to stat update on idle cpu
It was noted that the vm stat shepherd runs every 2 seconds and that the vmstat update is then scheduled 2 seconds in the future. This yields an interval of double the time interval which is not desired. Change the shepherd so that it does not delay the vmstat update on the other cpu. We stil have to use schedule_delayed_work since we are using a delayed_work_struct but we can set the delay to 0. Signed-off-by: Christoph Lameter <cl@linux.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Vinayak Menon <vinmenon@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
|
ba4877b9ca |
vmstat: do not use deferrable delayed work for vmstat_update
Vinayak Menon has reported that an excessive number of tasks was throttled in the direct reclaim inside too_many_isolated() because NR_ISOLATED_FILE was relatively high compared to NR_INACTIVE_FILE. However it turned out that the real number of NR_ISOLATED_FILE was 0 and the per-cpu vm_stat_diff wasn't transferred into the global counter. vmstat_work which is responsible for the sync is defined as deferrable delayed work which means that the defined timeout doesn't wake up an idle CPU. A CPU might stay in an idle state for a long time and general effort is to keep such a CPU in this state as long as possible which might lead to all sorts of troubles for vmstat consumers as can be seen with the excessive direct reclaim throttling. This patch basically reverts |
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Andrew Morton
|
3c48687109 |
mm/vmstat.c: fix/cleanup ifdefs
CONFIG_COMPACTION=y, CONFIG_DEBUG_FS=n: mm/vmstat.c:690: warning: 'frag_start' defined but not used mm/vmstat.c:702: warning: 'frag_next' defined but not used mm/vmstat.c:710: warning: 'frag_stop' defined but not used mm/vmstat.c:715: warning: 'walk_zones_in_node' defined but not used It's all a bit of a tangly mess and it's unclear why CONFIG_COMPACTION figures in there at all. Move frag_start/frag_next/frag_stop and migratetype_names[] into the existing CONFIG_PROC_FS block. walk_zones_in_node() gets a special ifdef. Also move the #include lines up to where #include lines live. [axel.lin@ingics.com: fix build error when !CONFIG_PROC_FS] Signed-off-by: Axel Lin <axel.lin@ingics.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Tested-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Davidlohr Bueso
|
f5f302e212 |
mm,vmacache: count number of system-wide flushes
These flushes deal with sequence number overflows, such as for long lived threads. These are rare, but interesting from a debugging PoV. As such, display the number of flushes when vmacache debugging is enabled. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Joonsoo Kim
|
48c96a3685 |
mm/page_owner: keep track of page owners
This is the page owner tracking code which is introduced so far ago. It is resident on Andrew's tree, though, nobody tried to upstream so it remain as is. Our company uses this feature actively to debug memory leak or to find a memory hogger so I decide to upstream this feature. This functionality help us to know who allocates the page. When allocating a page, we store some information about allocation in extra memory. Later, if we need to know status of all pages, we can get and analyze it from this stored information. In previous version of this feature, extra memory is statically defined in struct page, but, in this version, extra memory is allocated outside of struct page. It enables us to turn on/off this feature at boottime without considerable memory waste. Although we already have tracepoint for tracing page allocation/free, using it to analyze page owner is rather complex. We need to enlarge the trace buffer for preventing overlapping until userspace program launched. And, launched program continually dump out the trace buffer for later analysis and it would change system behaviour with more possibility rather than just keeping it in memory, so bad for debug. Moreover, we can use page_owner feature further for various purposes. For example, we can use it for fragmentation statistics implemented in this patch. And, I also plan to implement some CMA failure debugging feature using this interface. I'd like to give the credit for all developers contributed this feature, but, it's not easy because I don't know exact history. Sorry about that. Below is people who has "Signed-off-by" in the patches in Andrew's tree. Contributor: Alexander Nyberg <alexn@dsv.su.se> Mel Gorman <mgorman@suse.de> Dave Hansen <dave@linux.vnet.ibm.com> Minchan Kim <minchan@kernel.org> Michal Nazarewicz <mina86@mina86.com> Andrew Morton <akpm@linux-foundation.org> Jungsoo Son <jungsoo.son@lge.com> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Dave Hansen <dave@sr71.net> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Jungsoo Son <jungsoo.son@lge.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Christoph Lameter
|
7cc36bbddd |
vmstat: on-demand vmstat workers V8
vmstat workers are used for folding counter differentials into the zone, per node and global counters at certain time intervals. They currently run at defined intervals on all processors which will cause some holdoff for processors that need minimal intrusion by the OS. The current vmstat_update mechanism depends on a deferrable timer firing every other second by default which registers a work queue item that runs on the local CPU, with the result that we have 1 interrupt and one additional schedulable task on each CPU every 2 seconds If a workload indeed causes VM activity or multiple tasks are running on a CPU, then there are probably bigger issues to deal with. However, some workloads dedicate a CPU for a single CPU bound task. This is done in high performance computing, in high frequency financial applications, in networking (Intel DPDK, EZchip NPS) and with the advent of systems with more and more CPUs over time, this may become more and more common to do since when one has enough CPUs one cares less about efficiently sharing a CPU with other tasks and more about efficiently monopolizing a CPU per task. The difference of having this timer firing and workqueue kernel thread scheduled per second can be enormous. An artificial test measuring the worst case time to do a simple "i++" in an endless loop on a bare metal system and under Linux on an isolated CPU with dynticks and with and without this patch, have Linux match the bare metal performance (~700 cycles) with this patch and loose by couple of orders of magnitude (~200k cycles) without it[*]. The loss occurs for something that just calculates statistics. For networking applications, for example, this could be the difference between dropping packets or sustaining line rate. Statistics are important and useful, but it would be great if there would be a way to not cause statistics gathering produce a huge performance difference. This patche does just that. This patch creates a vmstat shepherd worker that monitors the per cpu differentials on all processors. If there are differentials on a processor then a vmstat worker local to the processors with the differentials is created. That worker will then start folding the diffs in regular intervals. Should the worker find that there is no work to be done then it will make the shepherd worker monitor the differentials again. With this patch it is possible then to have periods longer than 2 seconds without any OS event on a "cpu" (hardware thread). The patch shows a very minor increased in system performance. hackbench -s 512 -l 2000 -g 15 -f 25 -P Results before the patch: Running in process mode with 15 groups using 50 file descriptors each (== 750 tasks) Each sender will pass 2000 messages of 512 bytes Time: 4.992 Running in process mode with 15 groups using 50 file descriptors each (== 750 tasks) Each sender will pass 2000 messages of 512 bytes Time: 4.971 Running in process mode with 15 groups using 50 file descriptors each (== 750 tasks) Each sender will pass 2000 messages of 512 bytes Time: 5.063 Hackbench after the patch: Running in process mode with 15 groups using 50 file descriptors each (== 750 tasks) Each sender will pass 2000 messages of 512 bytes Time: 4.973 Running in process mode with 15 groups using 50 file descriptors each (== 750 tasks) Each sender will pass 2000 messages of 512 bytes Time: 4.990 Running in process mode with 15 groups using 50 file descriptors each (== 750 tasks) Each sender will pass 2000 messages of 512 bytes Time: 4.993 [fengguang.wu@intel.com: cpu_stat_off can be static] Signed-off-by: Christoph Lameter <cl@linux.com> Reviewed-by: Gilad Ben-Yossef <gilad@benyossef.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tejun Heo <tj@kernel.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Mike Frysinger <vapier@gentoo.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Max Krasnyansky <maxk@qti.qualcomm.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Hugh Dickins <hughd@google.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Konstantin Khlebnikov
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09316c09dd |
mm/balloon_compaction: add vmstat counters and kpageflags bit
Always mark pages with PageBalloon even if balloon compaction is disabled and expose this mark in /proc/kpageflags as KPF_BALLOON. Also this patch adds three counters into /proc/vmstat: "balloon_inflate", "balloon_deflate" and "balloon_migrate". They accumulate balloon activity. Current size of balloon is (balloon_inflate - balloon_deflate) pages. All generic balloon code now gathered under option CONFIG_MEMORY_BALLOON. It should be selected by ballooning driver which wants use this feature. Currently virtio-balloon is the only user. Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com> Cc: Rafael Aquini <aquini@redhat.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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bb0b6dffa2 |
mm: vmscan: only update per-cpu thresholds for online CPU
When kswapd is awake reclaiming, the per-cpu stat thresholds are lowered to get more accurate counts to avoid breaching watermarks. This threshold update iterates over all possible CPUs which is unnecessary. Only online CPUs need to be updated. If a new CPU is onlined, refresh_zone_stat_thresholds() will set the thresholds correctly. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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0d5d823ab4 |
mm: move zone->pages_scanned into a vmstat counter
zone->pages_scanned is a write-intensive cache line during page reclaim
and it's also updated during page free. Move the counter into vmstat to
take advantage of the per-cpu updates and do not update it in the free
paths unless necessary.
On a small UMA machine running tiobench the difference is marginal. On
a 4-node machine the overhead is more noticable. Note that automatic
NUMA balancing was disabled for this test as otherwise the system CPU
overhead is unpredictable.
3.16.0-rc3 3.16.0-rc3 3.16.0-rc3
vanillarearrange-v5 vmstat-v5
User 746.94 759.78 774.56
System 65336.22 58350.98 32847.27
Elapsed 27553.52 27282.02 27415.04
Note that the overhead reduction will vary depending on where exactly
pages are allocated and freed.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Mel Gorman
|
3484b2de94 |
mm: rearrange zone fields into read-only, page alloc, statistics and page reclaim lines
The arrangement of struct zone has changed over time and now it has
reached the point where there is some inappropriate sharing going on.
On x86-64 for example
o The zone->node field is shared with the zone lock and zone->node is
accessed frequently from the page allocator due to the fair zone
allocation policy.
o span_seqlock is almost never used by shares a line with free_area
o Some zone statistics share a cache line with the LRU lock so
reclaim-intensive and allocator-intensive workloads can bounce the cache
line on a stat update
This patch rearranges struct zone to put read-only and read-mostly
fields together and then splits the page allocator intensive fields, the
zone statistics and the page reclaim intensive fields into their own
cache lines. Note that the type of lowmem_reserve changes due to the
watermark calculations being signed and avoiding a signed/unsigned
conversion there.
On the test configuration I used the overall size of struct zone shrunk
by one cache line. On smaller machines, this is not likely to be
noticable. However, on a 4-node NUMA machine running tiobench the
system CPU overhead is reduced by this patch.
3.16.0-rc3 3.16.0-rc3
vanillarearrange-v5r9
User 746.94 759.78
System 65336.22 58350.98
Elapsed 27553.52 27282.02
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Jianyu Zhan
|
bea04b0732 |
mm: use the light version __mod_zone_page_state in mlocked_vma_newpage()
mlocked_vma_newpage() is called with pte lock held(a spinlock), which implies preemtion disabled, and the vm stat counter is not modified from interrupt context, so we need not use an irq-safe mod_zone_page_state() here, using a light-weight version __mod_zone_page_state() would be OK. This patch also documents __mod_zone_page_state() and some of its callsites. The comment above __mod_zone_page_state() is from Hugh Dickins, and acked by Christoph. Most credits to Hugh and Christoph for the clarification on the usage of the __mod_zone_page_state(). [akpm@linux-foundation.org: coding-style fixes] Suggested-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Jianyu Zhan <nasa4836@gmail.com> Reviewed-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Christoph Lameter
|
7c8e0181e6 |
mm: replace __get_cpu_var uses with this_cpu_ptr
Replace places where __get_cpu_var() is used for an address calculation with this_cpu_ptr(). Signed-off-by: Christoph Lameter <cl@linux.com> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Davidlohr Bueso
|
4f115147ff |
mm,vmacache: add debug data
Introduce a CONFIG_DEBUG_VM_VMACACHE option to enable counting the cache hit rate -- exported in /proc/vmstat. Any updates to the caching scheme needs this kind of data, thus it can save some work re-implementing the counting all the time. Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds
|
467a9e1633 |
CPU hotplug notifiers registration fixes for 3.15-rc1
The purpose of this single series of commits from Srivatsa S Bhat (with a small piece from Gautham R Shenoy) touching multiple subsystems that use CPU hotplug notifiers is to provide a way to register them that will not lead to deadlocks with CPU online/offline operations as described in the changelog of commit |
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Dave Hansen
|
5509a5d27b |
drop_caches: add some documentation and info message
There is plenty of anecdotal evidence and a load of blog posts suggesting that using "drop_caches" periodically keeps your system running in "tip top shape". Perhaps adding some kernel documentation will increase the amount of accurate data on its use. If we are not shrinking caches effectively, then we have real bugs. Using drop_caches will simply mask the bugs and make them harder to find, but certainly does not fix them, nor is it an appropriate "workaround" to limit the size of the caches. On the contrary, there have been bug reports on issues that turned out to be misguided use of cache dropping. Dropping caches is a very drastic and disruptive operation that is good for debugging and running tests, but if it creates bug reports from production use, kernel developers should be aware of its use. Add a bit more documentation about it, a syslog message to track down abusers, and vmstat drop counters to help analyze problem reports. [akpm@linux-foundation.org: checkpatch fixes] [hannes@cmpxchg.org: add runtime suppression control] Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |