Commit Graph

3287 Commits

Author SHA1 Message Date
David S. Miller
36583eb54d Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Conflicts:
	drivers/net/ethernet/cadence/macb.c
	drivers/net/phy/phy.c
	include/linux/skbuff.h
	net/ipv4/tcp.c
	net/switchdev/switchdev.c

Switchdev was a case of RTNH_H_{EXTERNAL --> OFFLOAD}
renaming overlapping with net-next changes of various
sorts.

phy.c was a case of two changes, one adding a local
variable to a function whilst the second was removing
one.

tcp.c overlapped a deadlock fix with the addition of new tcp_info
statistic values.

macb.c involved the addition of two zyncq device entries.

skbuff.h involved adding back ipv4_daddr to nf_bridge_info
whilst net-next changes put two other existing members of
that struct into a union.

Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-23 01:22:35 -04:00
Michael Holzheu
fe59384495 test_bpf: Add backward jump test case
Currently the testsuite does not have a test case with a backward jump.
The s390x JIT (kernel 4.0) had a bug in that area.
So add one new test case for this now.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-22 15:10:51 -04:00
Herbert Xu
07ee0722bf rhashtable: Add cap on number of elements in hash table
We currently have no limit on the number of elements in a hash table.
This is a problem because some users (tipc) set a ceiling on the
maximum table size and when that is reached the hash table may
degenerate.  Others may encounter OOM when growing and if we allow
insertions when that happens the hash table perofrmance may also
suffer.

This patch adds a new paramater insecure_max_entries which becomes
the cap on the table.  If unset it defaults to max_size * 2.  If
it is also zero it means that there is no cap on the number of
elements in the table.  However, the table will grow whenever the
utilisation hits 100% and if that growth fails, you will get ENOMEM
on insertion.

As allowing oversubscription is potentially dangerous, the name
contains the word insecure.

Note that the cap is not a hard limit.  This is done for performance
reasons as enforcing a hard limit will result in use of atomic ops
that are heavier than the ones we currently use.

The reasoning is that we're only guarding against a gross over-
subscription of the table, rather than a small breach of the limit.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-16 18:08:26 -04:00
Michael Holzheu
56cbaa45dd test_bpf: fix sparse warnings
Fix several sparse warnings like:
lib/test_bpf.c:1824:25: sparse: constant 4294967295 is so big it is long
lib/test_bpf.c:1878:25: sparse: constant 0x0000ffffffff0000 is so big it is long

Fixes: cffc642d93 ("test_bpf: add 173 new testcases for eBPF")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-14 22:47:14 -04:00
Daniel Borkmann
a4afd37b26 test_bpf: add tests related to BPF_MAXINSNS
Couple of torture test cases related to the bug fixed in 0b59d8806a
("ARM: net: delegate filter to kernel interpreter when imm_offset()
return value can't fit into 12bits.").

I've added a helper to allocate and fill the insn space. Output on
x86_64 from my laptop:

test_bpf: #233 BPF_MAXINSNS: Maximum possible literals jited:0 7 PASS
test_bpf: #234 BPF_MAXINSNS: Single literal jited:0 8 PASS
test_bpf: #235 BPF_MAXINSNS: Run/add until end jited:0 11553 PASS
test_bpf: #236 BPF_MAXINSNS: Too many instructions PASS
test_bpf: #237 BPF_MAXINSNS: Very long jump jited:0 9 PASS
test_bpf: #238 BPF_MAXINSNS: Ctx heavy transformations jited:0 20329 20398 PASS
test_bpf: #239 BPF_MAXINSNS: Call heavy transformations jited:0 32178 32475 PASS
test_bpf: #240 BPF_MAXINSNS: Jump heavy test jited:0 10518 PASS

test_bpf: #233 BPF_MAXINSNS: Maximum possible literals jited:1 4 PASS
test_bpf: #234 BPF_MAXINSNS: Single literal jited:1 4 PASS
test_bpf: #235 BPF_MAXINSNS: Run/add until end jited:1 1625 PASS
test_bpf: #236 BPF_MAXINSNS: Too many instructions PASS
test_bpf: #237 BPF_MAXINSNS: Very long jump jited:1 8 PASS
test_bpf: #238 BPF_MAXINSNS: Ctx heavy transformations jited:1 3301 3174 PASS
test_bpf: #239 BPF_MAXINSNS: Call heavy transformations jited:1 24107 23491 PASS
test_bpf: #240 BPF_MAXINSNS: Jump heavy test jited:1 8651 PASS

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Nicolas Schichan <nschichan@freebox.fr>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-14 22:34:10 -04:00
David S. Miller
b04096ff33 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Four minor merge conflicts:

1) qca_spi.c renamed the local variable used for the SPI device
   from spi_device to spi, meanwhile the spi_set_drvdata() call
   got moved further up in the probe function.

2) Two changes were both adding new members to codel params
   structure, and thus we had overlapping changes to the
   initializer function.

3) 'net' was making a fix to sk_release_kernel() which is
   completely removed in 'net-next'.

4) In net_namespace.c, the rtnl_net_fill() call for GET operations
   had the command value fixed, meanwhile 'net-next' adjusted the
   argument signature a bit.

This also matches example merge resolutions posted by Stephen
Rothwell over the past two days.

Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-13 14:31:43 -04:00
Michael Holzheu
cffc642d93 test_bpf: add 173 new testcases for eBPF
add an exhaustive set of eBPF tests bringing total to:
test_bpf: Summary: 233 PASSED, 0 FAILED, [0/226 JIT'ed]

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-12 23:15:25 -04:00
Xi Wang
986ccfdbd9 test: bpf: extend "load 64-bit immediate" testcase
Extend the testcase to catch a signedness bug in the arm64 JIT:

test_bpf: #58 load 64-bit immediate jited:1 ret -1 != 1 FAIL (1 times)

This is useful to ensure other JITs won't have a similar bug.

Link: https://lkml.org/lkml/2015/5/8/458
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-11 11:02:27 -04:00
Linus Torvalds
02f0f5721e Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU fix from Ingo Molnar:
 "An RCU Kconfig fix that eliminates an annoying interactive kconfig
  question for CONFIG_RCU_TORTURE_TEST_SLOW_INIT"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rcu: Control grace-period delays directly from value
2015-05-06 10:26:37 -07:00
Joe Perches
01e76903f6 kasan: show gcc version requirements in Kconfig and Documentation
The documentation shows a need for gcc > 4.9.2, but it's really >=.  The
Kconfig entries don't show require versions so add them.  Correct a
latter/later typo too.  Also mention that gcc 5 required to catch out of
bounds accesses to global and stack variables.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-05-05 17:10:10 -07:00
Yury Norov
7d616e4ddb lib: delete lib/find_last_bit.c
The file lib/find_last_bit.c was no longer used and supposed to be
deleted by commit 8f6f19dd51 ("lib: move find_last_bit to
lib/find_next_bit.c") but that delete didn't happen.  This gets rid of
it.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-05-05 17:10:10 -07:00
Thomas Graf
6decd63aca rhashtable-test: Fix 64bit division
A 64bit division went in unnoticed. Use do_div() to accomodate
non 64bit architectures.

Reported-by: kbuild test robot
Fixes: 1aa661f5c3 ("rhashtable-test: Measure time to insert, remove & traverse entries")
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-05 19:30:47 -04:00
Thomas Graf
c936a79fc0 rhashtable: Simplify iterator code
Remove useless obj variable and goto logic.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-05 19:30:47 -04:00
Linus Torvalds
d9cee5d4f6 Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
Pull crypto fixes from Herbert Xu:
 "This fixes a build problem with bcm63xx and yet another fix to the
  memzero_explicit function to ensure that the memset is not elided"

* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  hwrng: bcm63xx - Fix driver compilation
  lib: make memzero_explicit more robust against dead store elimination
2015-05-05 09:03:52 -07:00
Daniel Borkmann
7829fb09a2 lib: make memzero_explicit more robust against dead store elimination
In commit 0b053c9518 ("lib: memzero_explicit: use barrier instead
of OPTIMIZER_HIDE_VAR"), we made memzero_explicit() more robust in
case LTO would decide to inline memzero_explicit() and eventually
find out it could be elimiated as dead store.

While using barrier() works well for the case of gcc, recent efforts
from LLVMLinux people suggest to use llvm as an alternative to gcc,
and there, Stephan found in a simple stand-alone user space example
that llvm could nevertheless optimize and thus elimitate the memset().
A similar issue has been observed in the referenced llvm bug report,
which is regarded as not-a-bug.

Based on some experiments, icc is a bit special on its own, while it
doesn't seem to eliminate the memset(), it could do so with an own
implementation, and then result in similar findings as with llvm.

The fix in this patch now works for all three compilers (also tested
with more aggressive optimization levels). Arguably, in the current
kernel tree it's more of a theoretical issue, but imho, it's better
to be pedantic about it.

It's clearly visible with gcc/llvm though, with the below code: if we
would have used barrier() only here, llvm would have omitted clearing,
not so with barrier_data() variant:

  static inline void memzero_explicit(void *s, size_t count)
  {
    memset(s, 0, count);
    barrier_data(s);
  }

  int main(void)
  {
    char buff[20];
    memzero_explicit(buff, sizeof(buff));
    return 0;
  }

  $ gcc -O2 test.c
  $ gdb a.out
  (gdb) disassemble main
  Dump of assembler code for function main:
   0x0000000000400400  <+0>: lea   -0x28(%rsp),%rax
   0x0000000000400405  <+5>: movq  $0x0,-0x28(%rsp)
   0x000000000040040e <+14>: movq  $0x0,-0x20(%rsp)
   0x0000000000400417 <+23>: movl  $0x0,-0x18(%rsp)
   0x000000000040041f <+31>: xor   %eax,%eax
   0x0000000000400421 <+33>: retq
  End of assembler dump.

  $ clang -O2 test.c
  $ gdb a.out
  (gdb) disassemble main
  Dump of assembler code for function main:
   0x00000000004004f0  <+0>: xorps  %xmm0,%xmm0
   0x00000000004004f3  <+3>: movaps %xmm0,-0x18(%rsp)
   0x00000000004004f8  <+8>: movl   $0x0,-0x8(%rsp)
   0x0000000000400500 <+16>: lea    -0x18(%rsp),%rax
   0x0000000000400505 <+21>: xor    %eax,%eax
   0x0000000000400507 <+23>: retq
  End of assembler dump.

As gcc, clang, but also icc defines __GNUC__, it's sufficient to define
this in compiler-gcc.h only to be picked up. For a fallback or otherwise
unsupported compiler, we define it as a barrier. Similarly, for ecc which
does not support gcc inline asm.

Reference: https://llvm.org/bugs/show_bug.cgi?id=15495
Reported-by: Stephan Mueller <smueller@chronox.de>
Tested-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Stephan Mueller <smueller@chronox.de>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: mancha security <mancha1@zoho.com>
Cc: Mark Charlebois <charlebm@gmail.com>
Cc: Behan Webster <behanw@converseincode.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2015-05-04 17:49:51 +08:00
Thomas Graf
67b7cbf420 rhashtable-test: Detect insertion failures
Account for failed inserts due to memory pressure or EBUSY and
ignore failed entries during the consistency check.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-03 23:08:54 -04:00
Thomas Graf
246b23a769 rhashtable-test: Use walker to test bucket statistics
As resizes may continue to run in the background, use walker to
ensure we see all entries. Also print the encountered number
of rehashes queued up while traversing.

This may lead to warnings due to entries being seen multiple
times. We consider them non-fatal.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-03 23:08:54 -04:00
Thomas Graf
fcc570207c rhashtable-test: Do not allocate individual test objects
By far the most expensive part of the selftest was the allocation
of entries. Using a static array allows to measure the rhashtable
operations.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-03 23:08:54 -04:00
Thomas Graf
c2c8a90166 rhashtable-test: Get rid of ptr in test_obj structure
This only blows up the size of the test structure for no gain
in test coverage. Reduces size of test_obj from 24 to 16 bytes.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-03 23:08:54 -04:00
Thomas Graf
1aa661f5c3 rhashtable-test: Measure time to insert, remove & traverse entries
Make test configurable by allowing to specify all relevant knobs
through module parameters.

Do several test runs and measure the average time it takes to
insert & remove all entries. Note, a deferred resize might still
continue to run in the background.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-03 23:08:53 -04:00
Thomas Graf
f54e84b6e9 rhashtable-test: Remove unused TEST_NEXPANDS
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-03 23:08:53 -04:00
Daniel Borkmann
327941f8d3 test_bpf: indicate whether bpf prog got jited in test suite
I think this is useful to verify whether a filter could be JITed or
not in case of bpf_prog_enable >= 1, which otherwise the test suite
doesn't tell besides taking a good peek at the performance numbers.

Nicolas Schichan reported a bug in the ARM JIT compiler that rejected
and waved the filter to the interpreter although it shouldn't have.
Nevertheless, the test passes as expected, but such information is
not visible.

It's i.e. useful for the remaining classic JITs, but also for
implementing remaining opcodes that are not yet present in eBPF JITs
(e.g. ARM64 waves some of them to the interpreter). This minor patch
allows to grep through dmesg to find those accordingly, but also
provides a total summary, i.e.: [<X>/53 JIT'ed]

  # echo 1 > /proc/sys/net/core/bpf_jit_enable
  # insmod lib/test_bpf.ko
  # dmesg | grep "jited:0"

dmesg example on the ARM issue with JIT rejection:

[...]
[   67.925387] test_bpf: #2 ADD_SUB_MUL_K jited:1 24 PASS
[   67.930889] test_bpf: #3 DIV_MOD_KX jited:0 794 PASS
[   67.943940] test_bpf: #4 AND_OR_LSH_K jited:1 20 20 PASS
[...]

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Nicolas Schichan <nschichan@freebox.fr>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-04-30 16:40:53 -04:00
Linus Torvalds
2decb2682f Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Pull networking fixes from David Miller:

 1) mlx4 doesn't check fully for supported valid RSS hash function, fix
    from Amir Vadai

 2) Off by one in ibmveth_change_mtu(), from David Gibson

 3) Prevent altera chip from reporting false error interrupts in some
    circumstances, from Chee Nouk Phoon

 4) Get rid of that stupid endless loop trying to allocate a FIN packet
    in TCP, and in the process kill deadlocks.  From Eric Dumazet

 5) Fix get_rps_cpus() crash due to wrong invalid-cpu value, also from
    Eric Dumazet

 6) Fix two bugs in async rhashtable resizing, from Thomas Graf

 7) Fix topology server listener socket namespace bug in TIPC, from Ying
    Xue

 8) Add some missing HAS_DMA kconfig dependencies, from Geert
    Uytterhoeven

 9) bgmac driver intends to force re-polling but does so by returning
    the wrong value from it's ->poll() handler.  Fix from Rafał Miłecki

10) When the creater of an rhashtable configures a max size for it,
    don't bark in the logs and drop insertions when that is exceeded.
    Fix from Johannes Berg

11) Recover from out of order packets in ppp mppe properly, from Sylvain
    Rochet

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (41 commits)
  bnx2x: really disable TPA if 'disable_tpa' option is set
  net:treewide: Fix typo in drivers/net
  net/mlx4_en: Prevent setting invalid RSS hash function
  mdio-mux-gpio: use new gpiod_get_array and gpiod_put_array functions
  netfilter; Add some missing default cases to switch statements in nft_reject.
  ppp: mppe: discard late packet in stateless mode
  ppp: mppe: sanity error path rework
  net/bonding: Make DRV macros private
  net: rfs: fix crash in get_rps_cpus()
  altera tse: add support for fixed-links.
  pxa168: fix double deallocation of managed resources
  net: fix crash in build_skb()
  net: eth: altera: Resolve false errors from MSGDMA to TSE
  ehea: Fix memory hook reference counting crashes
  net/tg3: Release IRQs on permanent error
  net: mdio-gpio: support access that may sleep
  inet: fix possible panic in reqsk_queue_unlink()
  rhashtable: don't attempt to grow when at max_size
  bgmac: fix requests for extra polling calls from NAPI
  tcp: avoid looping in tcp_send_fin()
  ...
2015-04-27 14:05:19 -07:00
Linus Torvalds
474095e46c md updates for 4.1
Highlights:
 
 - "experimental" code for managing md/raid1 across a cluster using
   DLM.  Code is not ready for general use and triggers a WARNING if used.
   However it is looking good and mostly done and having in mainline
   will help co-ordinate development.
 - RAID5/6 can now batch multiple (4K wide) stripe_heads so as to
   handle a full (chunk wide) stripe as a single unit.
 - RAID6 can now perform read-modify-write cycles which should
   help performance on larger arrays: 6 or more devices.
 - RAID5/6 stripe cache now grows and shrinks dynamically.  The value
   set is used as a minimum.
 - Resync is now allowed to go a little faster than the 'mininum' when
   there is competing IO.  How much faster depends on the speed of the
   devices, so the effective minimum should scale with device speed to
   some extent.
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v2
 
 iQIVAwUAVTbIxDnsnt1WYoG5AQIgAA//Z9FlEpkHcJJ75WGjrXgGJPyNTfEZOkoz
 jnD8PpBY2Afp341vMatd0XKErdEAhuPQmJMAa+tbxht6pk77X3fSzXghGA8FEafg
 yazn5pfBt6NXmepV4vhl/+LNYuWRxxLSA9EDm7wEg+tiO0UEts+a0w2TSXzcT1w+
 30Yi1EjAlTaJ5yjlBHUOtTXWE43D6RKnUr6FMy2dRlnzlFyDlezRMChWo9v6OkQF
 YqJ20FcvmJdLHY/6Yif3jvpm7eQecMqdCZENTvW/mJI86zqf6E+ToCYS1VNjfDnK
 ud61iU9eshu4WtNWBG6KLuHBD0grO1NaEL7/S16w1KdNJMhYgiK8WussvIAJEesA
 5SlETM7Y/1XFq8puwlAq2/tuPfhZ+TFxnAwce/C3hMTDcYAACnS/R6INFQXqGvy3
 nX1NLogrCycX8oqxv3jTFKLVqIVwlkSlHcUGzIWjcfCF37StcXFKI5q862agyg2+
 NNocFMuXhPPM1YcB9JJSo2nCsor4e9tTdVEZlFm2B3cc8LJ9BLWUMSoi1h7VK/1g
 P7psnPIjz7/cdI2TZTFjGTZ0Kvhx/NTYp41AZealDNxeGWUNM+5xGZnUF8QRBc/E
 0dGHtEAah834BDQFvNnJtuuh/s+KwbvswjNP+njoBsHjIQIvngDABpOwpIkdqF6r
 diQ2gUPnHN0=
 =OHG6
 -----END PGP SIGNATURE-----

Merge tag 'md/4.1' of git://neil.brown.name/md

Pull md updates from Neil Brown:
 "More updates that usual this time.  A few have performance impacts
  which hould mostly be positive, but RAID5 (in particular) can be very
  work-load ensitive...  We'll have to wait and see.

  Highlights:

   - "experimental" code for managing md/raid1 across a cluster using
     DLM.  Code is not ready for general use and triggers a WARNING if
     used.  However it is looking good and mostly done and having in
     mainline will help co-ordinate development.

   - RAID5/6 can now batch multiple (4K wide) stripe_heads so as to
     handle a full (chunk wide) stripe as a single unit.

   - RAID6 can now perform read-modify-write cycles which should help
     performance on larger arrays: 6 or more devices.

   - RAID5/6 stripe cache now grows and shrinks dynamically.  The value
     set is used as a minimum.

   - Resync is now allowed to go a little faster than the 'mininum' when
     there is competing IO.  How much faster depends on the speed of the
     devices, so the effective minimum should scale with device speed to
     some extent"

* tag 'md/4.1' of git://neil.brown.name/md: (58 commits)
  md/raid5: don't do chunk aligned read on degraded array.
  md/raid5: allow the stripe_cache to grow and shrink.
  md/raid5: change ->inactive_blocked to a bit-flag.
  md/raid5: move max_nr_stripes management into grow_one_stripe and drop_one_stripe
  md/raid5: pass gfp_t arg to grow_one_stripe()
  md/raid5: introduce configuration option rmw_level
  md/raid5: activate raid6 rmw feature
  md/raid6 algorithms: xor_syndrome() for SSE2
  md/raid6 algorithms: xor_syndrome() for generic int
  md/raid6 algorithms: improve test program
  md/raid6 algorithms: delta syndrome functions
  raid5: handle expansion/resync case with stripe batching
  raid5: handle io error of batch list
  RAID5: batch adjacent full stripe write
  raid5: track overwrite disk count
  raid5: add a new flag to track if a stripe can be batched
  raid5: use flex_array for scribble data
  md raid0: access mddev->queue (request queue member) conditionally because it is not set when accessed from dm-raid
  md: allow resync to go faster when there is competing IO.
  md: remove 'go_faster' option from ->sync_request()
  ...
2015-04-24 09:28:01 -07:00
Thomas Graf
a87b9ebf17 rhashtable: Do not schedule more than one rehash if we can't grow further
The current code currently only stops inserting rehashes into the
chain when no resizes are currently scheduled. As long as resizes
are scheduled and while inserting above the utilization watermark,
more and more rehashes will be scheduled.

This lead to a perfect DoS storm with thousands of rehashes
scheduled which lead to thousands of spinlocks to be taken
sequentially.

Instead, only allow either a series of resizes or a single rehash.
Drop any further rehashes and return -EBUSY.

Fixes: ccd57b1bd3 ("rhashtable: Add immediate rehash during insertion")
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-04-22 14:17:22 -04:00
Thomas Graf
e2307ed6cb rhashtable: Schedule async resize when sync realloc fails
When rhashtable_insert_rehash() fails with ENOMEM, this indicates that
we can't allocate the necessary memory in the current context but the
limits as set by the user would still allow to grow.

Thus attempt an async resize in the background where we can allocate
using GFP_KERNEL which is more likely to succeed. The insertion itself
will still fail to indicate pressure.

This fixes a bug where the table would never continue growing once the
utilization is above 100%.

Fixes: ccd57b1bd3 ("rhashtable: Add immediate rehash during insertion")
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-04-22 14:17:22 -04:00
Linus Torvalds
db4fd9c5d0 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc
Pull sparc fixes from David Miller:

 1) ldc_alloc_exp_dring() can be called from softints, so use
    GFP_ATOMIC.  From Sowmini Varadhan.

 2) Some minor warning/build fixups for the new iommu-common code on
    certain archs and with certain debug options enabled.  Also from
    Sowmini Varadhan.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
  sparc: Use GFP_ATOMIC in ldc_alloc_exp_dring() as it can be called in softirq context
  sparc64: Use M7 PMC write on all chips T4 and onward.
  iommu-common: rename iommu_pool_hash to iommu_hash_common
  iommu-common: fix x86_64 compiler warnings
2015-04-21 23:21:34 -07:00
Markus Stockhausen
a582564b24 md/raid6 algorithms: xor_syndrome() for SSE2
The second and (last) optimized XOR syndrome calculation. This version
supports right and left side optimization. All CPUs with architecture
older than Haswell will benefit from it.

It should be noted that SSE2 movntdq kills performance for memory areas
that are read and written simultaneously in chunks smaller than cache
line size. So use movdqa instead for P/Q writes in sse21 and sse22 XOR
functions.

Signed-off-by: Markus Stockhausen <stockhausen@collogia.de>
Signed-off-by: NeilBrown <neilb@suse.de>
2015-04-22 08:00:42 +10:00
Markus Stockhausen
9a5ce91d05 md/raid6 algorithms: xor_syndrome() for generic int
Start the algorithms with the very basic one. It is left and right
optimized. That means we can avoid all calculations for unneeded pages
above the right stop offset. For pages below the left start offset we
still need the syndrome multiplication but without reading data pages.

Signed-off-by: Markus Stockhausen <stockhausen@collogia.de>
Signed-off-by: NeilBrown <neilb@suse.de>
2015-04-22 08:00:42 +10:00
Markus Stockhausen
7e92e1d762 md/raid6 algorithms: improve test program
It is always helpful to have a test tool in place if we implement
new data critical algorithms. So add some test routines to the raid6
checker that can prove if the new xor_syndrome() works as expected.

Run through all permutations of start/stop pages per algorithm and
simulate a xor_syndrome() assisted rmw run. After each rmw check if
the recovery algorithm still confirms that the stripe is fine.

Signed-off-by: Markus Stockhausen <stockhausen@collogia.de>
Signed-off-by: NeilBrown <neilb@suse.de>
2015-04-22 08:00:42 +10:00
Markus Stockhausen
fe5cbc6e06 md/raid6 algorithms: delta syndrome functions
v3: s-o-b comment, explanation of performance and descision for
the start/stop implementation

Implementing rmw functionality for RAID6 requires optimized syndrome
calculation. Up to now we can only generate a complete syndrome. The
target P/Q pages are always overwritten. With this patch we provide
a framework for inplace P/Q modification. In the first place simply
fill those functions with NULL values.

xor_syndrome() has two additional parameters: start & stop. These
will indicate the first and last page that are changing during a
rmw run. That makes it possible to avoid several unneccessary loops
and speed up calculation. The caller needs to implement the following
logic to make the functions work.

1) xor_syndrome(disks, start, stop, ...): "Remove" all data of source
blocks inside P/Q between (and including) start and end.

2) modify any block with start <= block <= stop

3) xor_syndrome(disks, start, stop, ...): "Reinsert" all data of
source blocks into P/Q between (and including) start and end.

Pages between start and stop that won't be changed should be filled
with a pointer to the kernel zero page. The reasons for not taking NULL
pages are:

1) Algorithms cross the whole source data line by line. Thus avoid
additional branches.

2) Having a NULL page avoids calculating the XOR P parity but still
need calulation steps for the Q parity. Depending on the algorithm
unrolling that might be only a difference of 2 instructions per loop.

The benchmark numbers of the gen_syndrome() functions are displayed in
the kernel log. Do the same for the xor_syndrome() functions. This
will help to analyze performance problems and give an rough estimate
how well the algorithm works. The choice of the fastest algorithm will
still depend on the gen_syndrome() performance.

With the start/stop page implementation the speed can vary a lot in real
life. E.g. a change of page 0 & page 15 on a stripe will be harder to
compute than the case where page 0 & page 1 are XOR candidates. To be not
to enthusiatic about the expected speeds we will run a worse case test
that simulates a change on the upper half of the stripe. So we do:

1) calculation of P/Q for the upper pages

2) continuation of Q for the lower (empty) pages

Signed-off-by: Markus Stockhausen <stockhausen@collogia.de>
Signed-off-by: NeilBrown <neilb@suse.de>
2015-04-22 08:00:41 +10:00
Linus Torvalds
1fc149933f Char/Misc driver patches for 4.1-rc1
Here's the big char/misc driver patchset for 4.1-rc1.
 
 Lots of different driver subsystem updates here, nothing major, full
 details are in the shortlog below.
 
 All of this has been in linux-next for a while.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v2
 
 iEYEABECAAYFAlU2IMEACgkQMUfUDdst+yloDQCfbyIRL23WVAn9ckQse/y8gbjB
 OT4AoKTJbwndDP9Kb/lrj2tjd9QjNVrC
 =xhen
 -----END PGP SIGNATURE-----

Merge tag 'char-misc-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

Pull char/misc driver updates from Greg KH:
 "Here's the big char/misc driver patchset for 4.1-rc1.

  Lots of different driver subsystem updates here, nothing major, full
  details are in the shortlog.

  All of this has been in linux-next for a while"

* tag 'char-misc-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (133 commits)
  mei: trace: remove unused TRACE_SYSTEM_STRING
  DTS: ARM: OMAP3-N900: Add lis3lv02d support
  Documentation: DT: lis302: update wakeup binding
  lis3lv02d: DT: add wakeup unit 2 and wakeup threshold
  lis3lv02d: DT: use s32 to support negative values
  Drivers: hv: hv_balloon: correctly handle num_pages>INT_MAX case
  Drivers: hv: hv_balloon: correctly handle val.freeram<num_pages case
  mei: replace check for connection instead of transitioning
  mei: use mei_cl_is_connected consistently
  mei: fix mei_poll operation
  hv_vmbus: Add gradually increased delay for retries in vmbus_post_msg()
  Drivers: hv: hv_balloon: survive ballooning request with num_pages=0
  Drivers: hv: hv_balloon: eliminate jumps in piecewiese linear floor function
  Drivers: hv: hv_balloon: do not online pages in offline blocks
  hv: remove the per-channel workqueue
  hv: don't schedule new works in vmbus_onoffer()/vmbus_onoffer_rescind()
  hv: run non-blocking message handlers in the dispatch tasklet
  coresight: moving to new "hwtracing" directory
  coresight-tmc: Adding a status interface to sysfs
  coresight: remove the unnecessary configuration coresight-default-sink
  ...
2015-04-21 09:42:58 -07:00
Sowmini Varadhan
7b3372d4c2 iommu-common: rename iommu_pool_hash to iommu_hash_common
When CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set, the DEFINE_PER_CPU_SECTION
macro will define an extern __pcpu_unique_##name variable that could
conflict with the same definition in powerpc at this time. Avoid that
conflict by renaming iommu_pool_hash in iommu-common.c

Thanks to Guenter Roeck for catching this, and helping to test the fix.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-04-20 14:09:55 -04:00
Sowmini Varadhan
b0cc836d30 iommu-common: fix x86_64 compiler warnings
Declare iommu_large_alloc as static. Remove extern definition  for
iommu_tbl_pool_init().

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-04-20 14:09:55 -04:00
Linus Torvalds
6496edfce9 This is the final removal (after several years!) of the obsolete cpus_*
functions, prompted by their mis-use in staging.
 
 With these function removed, all cpu functions should only iterate to
 nr_cpu_ids, so we finally only allocate that many bits when cpumasks
 are allocated offstack.
 
 Thanks,
 Rusty.
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1
 
 iQIcBAABAgAGBQJVNPMuAAoJENkgDmzRrbjx7ZIP/j65e6xs1jEyXR3WOYSdTU1x
 bMo6JcII6O1oEZLgyKXgx9KiBg6uIIDta1NG/H/XIe354dwfHVsHvj5HHHQR5Xof
 iRrjLOaHj4XglI3hvsk0eEEl3/OBBLgyo9bUwDvMF1fmr/9tW4caMs3Op6n7Evzm
 YIvoAyeJ0A8BfEtOU5lXhcVIGmnHtSw0x6mdGXpXIBmWYQPCtdQP868s4lnl44w0
 bSNpAYdzEqg64Ph3SK0prgWPrn5+5EiaAhV7HZzENZ5+o0DAdIXWq/W7uHyCWPKH
 536cJDojec+nSUQkPYngngGprxrKO02aBcMw/3JGJ0tdCDj8yw3XAyVAFzz4hmMb
 Lkmyv4QHHIILLvJ4ZRH5KHWCjjVBg41LNCs2H3HnoxFACdm0lZYKHsUAh2ucBVtU
 Wb/eHmLxOG43UIkpX4yrhy3SfE1ZdnOVzEzOzPXtr51t8ojqk+bLFe/hJ6EkzrQX
 X+90qHfBq+PMJlAnc3zdXHjxoJrL6KPWVwVvFrNeibgEKtVvy/BiwZkS6QceC1Ea
 TatOYA5r6awFVHHQCooN1DGAxN5Juvu2SmdnTUA9ymsCNDghj1YUoAKRNP81u8Sa
 pe3hco/63iCuPna+vlwNDU6SgsaMk9m0p+1n1BiDIfVJIkWYCNeG+u2gQkzbDKlQ
 AJuKKQv1QuZiF0ylZ0wq
 =VAgA
 -----END PGP SIGNATURE-----

Merge tag 'cpumask-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

Pull final removal of deprecated cpus_* cpumask functions from Rusty Russell:
 "This is the final removal (after several years!) of the obsolete
  cpus_* functions, prompted by their mis-use in staging.

  With these function removed, all cpu functions should only iterate to
  nr_cpu_ids, so we finally only allocate that many bits when cpumasks
  are allocated offstack"

* tag 'cpumask-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (25 commits)
  cpumask: remove __first_cpu / __next_cpu
  cpumask: resurrect CPU_MASK_CPU0
  linux/cpumask.h: add typechecking to cpumask_test_cpu
  cpumask: only allocate nr_cpumask_bits.
  Fix weird uses of num_online_cpus().
  cpumask: remove deprecated functions.
  mips: fix obsolete cpumask_of_cpu usage.
  x86: fix more deprecated cpu function usage.
  ia64: remove deprecated cpus_ usage.
  powerpc: fix deprecated CPU_MASK_CPU0 usage.
  CPU_MASK_ALL/CPU_MASK_NONE: remove from deprecated region.
  staging/lustre/o2iblnd: Don't use cpus_weight
  staging/lustre/libcfs: replace deprecated cpus_ calls with cpumask_
  staging/lustre/ptlrpc: Do not use deprecated cpus_* functions
  blackfin: fix up obsolete cpu function usage.
  parisc: fix up obsolete cpu function usage.
  tile: fix up obsolete cpu function usage.
  arm64: fix up obsolete cpu function usage.
  mips: fix up obsolete cpu function usage.
  x86: fix up obsolete cpu function usage.
  ...
2015-04-20 10:19:03 -07:00
Linus Torvalds
17974c054d hexdump: avoid warning in test function
The test_data_1_le[] array is a const array of const char *.  To avoid
dropping any const information, we need to use "const char * const *",
not just "const char **".

I'm not sure why the different test arrays end up having different
const'ness, but let's make the pointer we use to traverse them as const
as possible, since we modify neither the array of pointers _or_ the
pointers we find in the array.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-19 13:48:40 -07:00
Rusty Russell
e4afa120c9 cpumask: remove __first_cpu / __next_cpu
They were for use by the deprecated first_cpu() and next_cpu() wrappers,
but sparc used them directly.

They're now replaced by cpumask_first / cpumask_next.  And __next_cpu_nr
is completely obsolete.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: David S. Miller <davem@davemloft.net>
2015-04-19 14:35:32 +09:30
Sowmini Varadhan
2f0c0fdc08 iommu-common: Fix PARISC compile-time warnings
Fixes warnings due to
- no DMA_ERROR_CODE on PARISC,
- sizeof (unsigned long) == 4 bytes on PARISC.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-04-18 12:34:50 -07:00
Sowmini Varadhan
ff7d37a502 Break up monolithic iommu table/lock into finer graularity pools and lock
Investigation of multithreaded iperf experiments on an ethernet
interface show the iommu->lock as the hottest lock identified by
lockstat, with something of the order of  21M contentions out of
27M acquisitions, and an average wait time of 26 us for the lock.
This is not efficient. A more scalable design is to follow the ppc
model, where the iommu_map_table has multiple pools, each stretching
over a segment of the map, and with a separate lock for each pool.
This model allows for better parallelization of the iommu map search.

This patch adds the iommu range alloc/free function infrastructure.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-04-18 12:32:59 -07:00
David S. Miller
c12f048ffd sparc: Revert generic IOMMU allocator.
I applied the wrong version of this patch series, V4 instead
of V10, due to a patchwork bundling snafu.

Signed-off-by: David S. Miller <davem@davemloft.net>
2015-04-18 12:31:25 -07:00
Ingo Molnar
cb0f3f320d Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/urgent
Pull RCU fix from Paul E. McKenney:

 "This series contains a single change that fixes Kconfig asking pointless
  questions."

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-18 14:49:41 +02:00
Linus Torvalds
e2fdae7e7c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc
Pull sparc updates from David Miller:
 "The PowerPC folks have a really nice scalable IOMMU pool allocator
  that we wanted to make use of for sparc.  So here we have a series
  that abstracts out their code into a common layer that anyone can make
  use of.

  Sparc is converted, and the PowerPC folks have reviewed and ACK'd this
  series and plan to convert PowerPC over as well"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
  iommu-common: Fix PARISC compile-time warnings
  sparc: Make LDC use common iommu poll management functions
  sparc: Make sparc64 use scalable lib/iommu-common.c functions
  sparc: Break up monolithic iommu table/lock into finer graularity pools and lock
2015-04-17 16:19:26 -04:00
Sowmini Varadhan
cb97201cb0 iommu-common: Fix PARISC compile-time warnings
Fixes warnings due to
- no DMA_ERROR_CODE on PARISC,
- sizeof (unsigned long) == 4 bytes on PARISC.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-04-17 15:24:36 -04:00
Linus Torvalds
54e514b91b Merge branch 'akpm' (patches from Andrew)
Merge third patchbomb from Andrew Morton:

 - various misc things

 - a couple of lib/ optimisations

 - provide DIV_ROUND_CLOSEST_ULL()

 - checkpatch updates

 - rtc tree

 - befs, nilfs2, hfs, hfsplus, fatfs, adfs, affs, bfs

 - ptrace fixes

 - fork() fixes

 - seccomp cleanups

 - more mmap_sem hold time reductions from Davidlohr

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (138 commits)
  proc: show locks in /proc/pid/fdinfo/X
  docs: add missing and new /proc/PID/status file entries, fix typos
  drivers/rtc/rtc-at91rm9200.c: make IO endian agnostic
  Documentation/spi/spidev_test.c: fix warning
  drivers/rtc/rtc-s5m.c: allow usage on device type different than main MFD type
  .gitignore: ignore *.tar
  MAINTAINERS: add Mediatek SoC mailing list
  tomoyo: reduce mmap_sem hold for mm->exe_file
  powerpc/oprofile: reduce mmap_sem hold for exe_file
  oprofile: reduce mmap_sem hold for mm->exe_file
  mips: ip32: add platform data hooks to use DS1685 driver
  lib/Kconfig: fix up HAVE_ARCH_BITREVERSE help text
  x86: switch to using asm-generic for seccomp.h
  sparc: switch to using asm-generic for seccomp.h
  powerpc: switch to using asm-generic for seccomp.h
  parisc: switch to using asm-generic for seccomp.h
  mips: switch to using asm-generic for seccomp.h
  microblaze: use asm-generic for seccomp.h
  arm: use asm-generic for seccomp.h
  seccomp: allow COMPAT sigreturn overrides
  ...
2015-04-17 09:04:38 -04:00
Andrew Morton
9e522c0d28 lib/Kconfig: fix up HAVE_ARCH_BITREVERSE help text
Cc: Yalin Wang <yalin.wang@sonymobile.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-17 09:04:10 -04:00
Sergey Senozhatsky
534b483a86 cpumask: don't perform while loop in cpumask_next_and()
cpumask_next_and() is looking for cpumask_next() in src1 in a loop and
tests if found cpu is also present in src2. remove that loop, perform
cpumask_and() of src1 and src2 first and use that new mask to find
cpumask_next().

Apart from removing while loop, ./bloat-o-meter on x86_64 shows
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-8 (-8)
function                                     old     new   delta
cpumask_next_and                              62      54      -8

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Amir Vadai <amirv@mellanox.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-17 09:04:08 -04:00
Yury Norov
2afe27c718 lib/bitmap.c: bitmap_[empty,full]: remove code duplication
bitmap_empty() has its own implementation.  But it's clearly as simple as:

	find_first_bit(src, nbits) == nbits

The same is true for 'bitmap_full'.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Cc: George Spelvin <linux@horizon.com>
Cc: Alexey Klimov <klimov.linux@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-17 09:03:56 -04:00
Rasmus Villemoes
675cf53c1d lib/vsprintf.c: improve put_dec_trunc8 slightly
I hadn't had enough coffee when I wrote this. Currently, the final
increment of buf depends on the value loaded from the table, and
causes gcc to emit a cmov immediately before the return. It is smarter
to let it depend on r, since the increment can then be computed in
parallel with the final load/store pair. It also shaves 16 bytes of
.text.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-17 09:03:55 -04:00
Sebastian Ott
a7a2c02a40 lib/dma-debug: fix bucket_find_contain()
bucket_find_contain() will search the bucket list for a dma_debug_entry.
When the entry isn't found it needs to search other buckets too, since
only the start address of a dma range is hashed (which might be in a
different bucket).

A copy of the dma_debug_entry is used to get the previous hash bucket
but when its list is searched the original dma_debug_entry is to be used
not its modified copy.

This fixes false "device driver tries to sync DMA memory it has not allocated"
warnings.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Horia Geanta <horia.geanta@freescale.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-17 09:03:54 -04:00
Rasmus Villemoes
7c43d9a30c lib/vsprintf.c: even faster binary to decimal conversion
The most expensive part of decimal conversion is the divisions by 10
(albeit done using reciprocal multiplication with appropriately chosen
constants).  I decided to see if one could eliminate around half of
these multiplications by emitting two digits at a time, at the cost of a
200 byte lookup table, and it does indeed seem like there is something
to be gained, especially on 64 bits.  Microbenchmarking shows
improvements ranging from -50% (for numbers uniformly distributed in [0,
2^64-1]) to -25% (for numbers heavily biased toward the smaller end, a
more realistic distribution).

On a larger scale, perf shows that top, one of the big consumers of /proc
data, uses 0.5-1.0% fewer cpu cycles.

I had to jump through some hoops to get the 32 bit code to compile and run
on my 64 bit machine, so I'm not sure how relevant these numbers are, but
just for comparison the microbenchmark showed improvements between -30%
and -10%.

The bloat-o-meter costs are around 150 bytes (the generated code is a
little smaller, so it's not the full 200 bytes) on both 32 and 64 bit.
I'm aware that extra cache misses won't show up in a microbenchmark as
used above, but on the other hand decimal conversions often happen in bulk
(for example in the case of top).

I have of course tested that the new code generates the same output as the
old, for both the first and last 1e10 numbers in [0,2^64-1] and 4e9
'random' numbers in-between.

Test and verification code on github: https://github.com/Villemoes/dec.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Tested-by: Jeff Epler <jepler@unpythonic.net>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-17 09:03:54 -04:00