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linux/kernel/sched/features.h

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sched: Implement a gentler fair-sleepers feature Add back FAIR_SLEEPERS and GENTLE_FAIR_SLEEPERS. FAIR_SLEEPERS is the old logic: credit sleepers with their sleep time. GENTLE_FAIR_SLEEPERS dampens this a bit: 50% of their sleep time gets credited. The hope here is to still give the benefits of fair-sleepers logic (quick wakeups, etc.) while not allow them to have 100% of their sleep time as if they were running. Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-16 06:54:45 +00:00
/*
* Only give sleepers 50% of their service deficit. This allows
* them to run sooner, but does not allow tons of sleepers to
* rip the spread apart.
*/
sched: Use jump_labels for sched_feat Now that we initialize jump_labels before sched_init() we can use them for the debug features without having to worry about a window where they have the wrong setting. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-vpreo4hal9e0kzqmg5y0io2k@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-06 12:20:14 +00:00
SCHED_FEAT(GENTLE_FAIR_SLEEPERS, true)
sched: Add come comments to the sched features Add text... Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-11 10:31:23 +00:00
/*
* Place new tasks ahead so that they do not starve already running
* tasks
*/
sched: Use jump_labels for sched_feat Now that we initialize jump_labels before sched_init() we can use them for the debug features without having to worry about a window where they have the wrong setting. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-vpreo4hal9e0kzqmg5y0io2k@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-06 12:20:14 +00:00
SCHED_FEAT(START_DEBIT, true)
sched: Add come comments to the sched features Add text... Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-11 10:31:23 +00:00
/*
* Prefer to schedule the task we woke last (assuming it failed
* wakeup-preemption), since its likely going to consume data we
* touched, increases cache locality.
*/
sched: Use jump_labels for sched_feat Now that we initialize jump_labels before sched_init() we can use them for the debug features without having to worry about a window where they have the wrong setting. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-vpreo4hal9e0kzqmg5y0io2k@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-06 12:20:14 +00:00
SCHED_FEAT(NEXT_BUDDY, false)
sched: Add come comments to the sched features Add text... Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-11 10:31:23 +00:00
/*
* Prefer to schedule the task that ran last (when we did
* wake-preempt) as that likely will touch the same data, increases
* cache locality.
*/
sched: Use jump_labels for sched_feat Now that we initialize jump_labels before sched_init() we can use them for the debug features without having to worry about a window where they have the wrong setting. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-vpreo4hal9e0kzqmg5y0io2k@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-06 12:20:14 +00:00
SCHED_FEAT(LAST_BUDDY, true)
sched: Add come comments to the sched features Add text... Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-11 10:31:23 +00:00
/*
* Consider buddies to be cache hot, decreases the likelyness of a
* cache buddy being migrated away, increases cache locality.
*/
sched: Use jump_labels for sched_feat Now that we initialize jump_labels before sched_init() we can use them for the debug features without having to worry about a window where they have the wrong setting. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-vpreo4hal9e0kzqmg5y0io2k@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-06 12:20:14 +00:00
SCHED_FEAT(CACHE_HOT_BUDDY, true)
sched: Add come comments to the sched features Add text... Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-11 10:31:23 +00:00
sched: Add WAKEUP_PREEMPTION feature flag, on by default As per the recent discussion with Mike and Linus, make it easier to test with/without this feature. No change in default behavior. Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-izoxq4haeg4mTognnDbwcevt@git.kernel.org
2012-10-14 12:28:50 +00:00
/*
* Allow wakeup-time preemption of the current task:
*/
SCHED_FEAT(WAKEUP_PREEMPTION, true)
sched: Feature to disable APERF/MPERF cpu_power I suspect a feed-back loop between cpuidle and the aperf/mperf cpu_power bits, where when we have idle C-states lower the ratio, which leads to lower cpu_power and then less load, which generates more idle time, etc.. Put in a knob to disable it. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-03 11:20:03 +00:00
/*
* Use arch dependent cpu power functions
*/
sched: cpu_power: enable ARCH_POWER Heteregeneous ARM platform uses arch_scale_freq_power function to reflect the relative capacity of each core Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1341826026-6504-6-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-07-09 09:27:06 +00:00
SCHED_FEAT(ARCH_POWER, true)
sched: Feature to disable APERF/MPERF cpu_power I suspect a feed-back loop between cpuidle and the aperf/mperf cpu_power bits, where when we have idle C-states lower the ratio, which leads to lower cpu_power and then less load, which generates more idle time, etc.. Put in a knob to disable it. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-03 11:20:03 +00:00
sched: Use jump_labels for sched_feat Now that we initialize jump_labels before sched_init() we can use them for the debug features without having to worry about a window where they have the wrong setting. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-vpreo4hal9e0kzqmg5y0io2k@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-06 12:20:14 +00:00
SCHED_FEAT(HRTICK, false)
SCHED_FEAT(DOUBLE_TICK, false)
SCHED_FEAT(LB_BIAS, true)
sched: Add come comments to the sched features Add text... Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-11 10:31:23 +00:00
/*
* Spin-wait on mutex acquisition when the mutex owner is running on
* another cpu -- assumes that when the owner is running, it will soon
* release the lock. Decreases scheduling overhead.
*/
sched: Use jump_labels for sched_feat Now that we initialize jump_labels before sched_init() we can use them for the debug features without having to worry about a window where they have the wrong setting. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-vpreo4hal9e0kzqmg5y0io2k@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-06 12:20:14 +00:00
SCHED_FEAT(OWNER_SPIN, true)
sched: Remove irq time from available CPU power The idea was suggested by Peter Zijlstra here: http://marc.info/?l=linux-kernel&m=127476934517534&w=2 irq time is technically not available to the tasks running on the CPU. This patch removes irq time from CPU power piggybacking on sched_rt_avg_update(). Tested this by keeping CPU X busy with a network intensive task having 75% oa a single CPU irq processing (hard+soft) on a 4-way system. And start seven cycle soakers on the system. Without this change, there will be two tasks on each CPU. With this change, there is a single task on irq busy CPU X and remaining 7 tasks are spread around among other 3 CPUs. Signed-off-by: Venkatesh Pallipadi <venki@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1286237003-12406-8-git-send-email-venki@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-10-05 00:03:22 +00:00
/*
sched: adjust scheduler cpu power for stolen time This patch makes update_rq_clock() aware of steal time. The mechanism of operation is not different from irq_time, and follows the same principles. This lives in a CONFIG option itself, and can be compiled out independently of the rest of steal time reporting. The effect of disabling it is that the scheduler will still report steal time (that cannot be disabled), but won't use this information for cpu power adjustments. Everytime update_rq_clock_task() is invoked, we query information about how much time was stolen since last call, and feed it into sched_rt_avg_update(). Although steal time reporting in account_process_tick() keeps track of the last time we read the steal clock, in prev_steal_time, this patch do it independently using another field, prev_steal_time_rq. This is because otherwise, information about time accounted in update_process_tick() would never reach us in update_rq_clock(). Signed-off-by: Glauber Costa <glommer@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Tested-by: Eric B Munson <emunson@mgebm.net> CC: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> CC: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2011-07-11 19:28:18 +00:00
* Decrement CPU power based on time not spent running tasks
sched: Remove irq time from available CPU power The idea was suggested by Peter Zijlstra here: http://marc.info/?l=linux-kernel&m=127476934517534&w=2 irq time is technically not available to the tasks running on the CPU. This patch removes irq time from CPU power piggybacking on sched_rt_avg_update(). Tested this by keeping CPU X busy with a network intensive task having 75% oa a single CPU irq processing (hard+soft) on a 4-way system. And start seven cycle soakers on the system. Without this change, there will be two tasks on each CPU. With this change, there is a single task on irq busy CPU X and remaining 7 tasks are spread around among other 3 CPUs. Signed-off-by: Venkatesh Pallipadi <venki@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1286237003-12406-8-git-send-email-venki@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-10-05 00:03:22 +00:00
*/
sched: Use jump_labels for sched_feat Now that we initialize jump_labels before sched_init() we can use them for the debug features without having to worry about a window where they have the wrong setting. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-vpreo4hal9e0kzqmg5y0io2k@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-06 12:20:14 +00:00
SCHED_FEAT(NONTASK_POWER, true)
sched: Move the second half of ttwu() to the remote cpu Now that we've removed the rq->lock requirement from the first part of ttwu() and can compute placement without holding any rq->lock, ensure we execute the second half of ttwu() on the actual cpu we want the task to run on. This avoids having to take rq->lock and doing the task enqueue remotely, saving lots on cacheline transfers. As measured using: http://oss.oracle.com/~mason/sembench.c $ for i in /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor ; do echo performance > $i; done $ echo 4096 32000 64 128 > /proc/sys/kernel/sem $ ./sembench -t 2048 -w 1900 -o 0 unpatched: run time 30 seconds 647278 worker burns per second patched: run time 30 seconds 816715 worker burns per second Reviewed-by: Frank Rowand <frank.rowand@am.sony.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110405152729.515897185@chello.nl
2011-04-05 15:23:58 +00:00
/*
* Queue remote wakeups on the target CPU and process them
* using the scheduler IPI. Reduces rq->lock contention/bounces.
*/
sched: Use jump_labels for sched_feat Now that we initialize jump_labels before sched_init() we can use them for the debug features without having to worry about a window where they have the wrong setting. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-vpreo4hal9e0kzqmg5y0io2k@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-06 12:20:14 +00:00
SCHED_FEAT(TTWU_QUEUE, true)
sched: Allow for overlapping sched_domain spans Allow for sched_domain spans that overlap by giving such domains their own sched_group list instead of sharing the sched_groups amongst each-other. This is needed for machines with more than 16 nodes, because sched_domain_node_span() will generate a node mask from the 16 nearest nodes without regard if these masks have any overlap. Currently sched_domains have a sched_group that maps to their child sched_domain span, and since there is no overlap we share the sched_group between the sched_domains of the various CPUs. If however there is overlap, we would need to link the sched_group list in different ways for each cpu, and hence sharing isn't possible. In order to solve this, allocate private sched_groups for each CPU's sched_domain but have the sched_groups share a sched_group_power structure such that we can uniquely track the power. Reported-and-tested-by: Anton Blanchard <anton@samba.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-08bxqw9wis3qti9u5inifh3y@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-15 08:35:52 +00:00
sched: Use jump_labels for sched_feat Now that we initialize jump_labels before sched_init() we can use them for the debug features without having to worry about a window where they have the wrong setting. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-vpreo4hal9e0kzqmg5y0io2k@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-06 12:20:14 +00:00
SCHED_FEAT(FORCE_SD_OVERLAP, false)
SCHED_FEAT(RT_RUNTIME_SHARE, true)
sched: Fix more load-balancing fallout Commits 367456c756a6 ("sched: Ditch per cgroup task lists for load-balancing") and 5d6523ebd ("sched: Fix load-balance wreckage") left some more wreckage. By setting loop_max unconditionally to ->nr_running load-balancing could take a lot of time on very long runqueues (hackbench!). So keep the sysctl as max limit of the amount of tasks we'll iterate. Furthermore, the min load filter for migration completely fails with cgroups since inequality in per-cpu state can easily lead to such small loads :/ Furthermore the change to add new tasks to the tail of the queue instead of the head seems to have some effect.. not quite sure I understand why. Combined these fixes solve the huge hackbench regression reported by Tim when hackbench is ran in a cgroup. Reported-by: Tim Chen <tim.c.chen@linux.intel.com> Acked-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/1335365763.28150.267.camel@twins [ got rid of the CONFIG_PREEMPT tuning and made small readability edits ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-04-17 11:38:40 +00:00
SCHED_FEAT(LB_MIN, false)
mm: numa: Add fault driven placement and migration NOTE: This patch is based on "sched, numa, mm: Add fault driven placement and migration policy" but as it throws away all the policy to just leave a basic foundation I had to drop the signed-offs-by. This patch creates a bare-bones method for setting PTEs pte_numa in the context of the scheduler that when faulted later will be faulted onto the node the CPU is running on. In itself this does nothing useful but any placement policy will fundamentally depend on receiving hints on placement from fault context and doing something intelligent about it. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com>
2012-10-25 12:16:43 +00:00
/*
mm: sched: numa: Control enabling and disabling of NUMA balancing This patch adds Kconfig options and kernel parameters to allow the enabling and disabling of automatic NUMA balancing. The existance of such a switch was and is very important when debugging problems related to transparent hugepages and we should have the same for automatic NUMA placement. Signed-off-by: Mel Gorman <mgorman@suse.de>
2012-11-22 11:16:36 +00:00
* Apply the automatic NUMA scheduling policy. Enabled automatically
* at runtime if running on a NUMA machine. Can be controlled via
mm: sched: numa: Delay PTE scanning until a task is scheduled on a new node Due to the fact that migrations are driven by the CPU a task is running on there is no point tracking NUMA faults until one task runs on a new node. This patch tracks the first node used by an address space. Until it changes, PTE scanning is disabled and no NUMA hinting faults are trapped. This should help workloads that are short-lived, do not care about NUMA placement or have bound themselves to a single node. This takes advantage of the logic in "mm: sched: numa: Implement slow start for working set sampling" to delay when the checks are made. This will take advantage of processes that set their CPU and node bindings early in their lifetime. It will also potentially allow any initial load balancing to take place. Signed-off-by: Mel Gorman <mgorman@suse.de>
2012-11-22 14:40:03 +00:00
* numa_balancing=. Allow PTE scanning to be forced on UMA machines
* for debugging the core machinery.
mm: numa: Add fault driven placement and migration NOTE: This patch is based on "sched, numa, mm: Add fault driven placement and migration policy" but as it throws away all the policy to just leave a basic foundation I had to drop the signed-offs-by. This patch creates a bare-bones method for setting PTEs pte_numa in the context of the scheduler that when faulted later will be faulted onto the node the CPU is running on. In itself this does nothing useful but any placement policy will fundamentally depend on receiving hints on placement from fault context and doing something intelligent about it. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com>
2012-10-25 12:16:43 +00:00
*/
#ifdef CONFIG_NUMA_BALANCING
mm: sched: numa: Control enabling and disabling of NUMA balancing This patch adds Kconfig options and kernel parameters to allow the enabling and disabling of automatic NUMA balancing. The existance of such a switch was and is very important when debugging problems related to transparent hugepages and we should have the same for automatic NUMA placement. Signed-off-by: Mel Gorman <mgorman@suse.de>
2012-11-22 11:16:36 +00:00
SCHED_FEAT(NUMA, false)
mm: sched: numa: Delay PTE scanning until a task is scheduled on a new node Due to the fact that migrations are driven by the CPU a task is running on there is no point tracking NUMA faults until one task runs on a new node. This patch tracks the first node used by an address space. Until it changes, PTE scanning is disabled and no NUMA hinting faults are trapped. This should help workloads that are short-lived, do not care about NUMA placement or have bound themselves to a single node. This takes advantage of the logic in "mm: sched: numa: Implement slow start for working set sampling" to delay when the checks are made. This will take advantage of processes that set their CPU and node bindings early in their lifetime. It will also potentially allow any initial load balancing to take place. Signed-off-by: Mel Gorman <mgorman@suse.de>
2012-11-22 14:40:03 +00:00
SCHED_FEAT(NUMA_FORCE, false)
mm: numa: Add fault driven placement and migration NOTE: This patch is based on "sched, numa, mm: Add fault driven placement and migration policy" but as it throws away all the policy to just leave a basic foundation I had to drop the signed-offs-by. This patch creates a bare-bones method for setting PTEs pte_numa in the context of the scheduler that when faulted later will be faulted onto the node the CPU is running on. In itself this does nothing useful but any placement policy will fundamentally depend on receiving hints on placement from fault context and doing something intelligent about it. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com>
2012-10-25 12:16:43 +00:00
#endif
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