Граф коммитов

20 Коммитов

Автор SHA1 Сообщение Дата
Tommi Rantala 7b919a5310 perf bench: Clear struct sigaction before sigaction() syscall
Avoid garbage in sigaction structs used in sigaction() syscalls.
Valgrind is complaining about it.

Signed-off-by: Tommi Rantala <tommi.t.rantala@nokia.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Changbin Du <changbin.du@intel.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lore.kernel.org/lkml/20200305083714.9381-4-tommi.t.rantala@nokia.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2020-03-06 08:30:47 -03:00
Arnaldo Carvalho de Melo 87ffb6c640 perf env: Remove needless cpumap.h header
Only a 'struct perf_cmp_map' forward allocation is necessary, fix the
places that need the header but were getting it indirectly, by luck,
from env.h.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-3sj3n534zghxhk7ygzeaqlx9@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-09-20 09:19:21 -03:00
Jiri Olsa 9c3516d1b8 libperf: Add perf_cpu_map__new()/perf_cpu_map__read() functions
Moving the following functions from tools/perf:

  cpu_map__new()
  cpu_map__read()

to libperf with the following names:

  perf_cpu_map__new()
  perf_cpu_map__read()

Committer notes:

Fixed up this one:

  tools/perf/arch/arm/util/cs-etm.c

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190721112506.12306-44-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-07-29 18:34:45 -03:00
Jiri Olsa f854839ba2 perf cpu_map: Rename struct cpu_map to struct perf_cpu_map
Rename struct cpu_map to struct perf_cpu_map, so it could be part of
libperf.

Committer notes:

Added fixes for arm64, provided by Jiri.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190721112506.12306-3-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-07-29 18:34:42 -03:00
Davidlohr Bueso 3b2323c2c1 perf bench futex: Use cpumaps
It was reported that the whole futex bench breaks when dealing with
non-contiguously numbered cpus.

$ echo 0 | sudo tee /sys/devices/system/cpu/cpu3/online
$ ./perf bench futex all
 perf: pthread_create: Operation not permitted
 Run summary [PID 14934]: 7 threads, each ....

James had implemented an approach with cpumaps that use an in house
flavor. Instead of re-inventing the wheel, I've redone the patch such
that we use the perf's util/cpumap.c interface instead.

Applies to all futex benchmarks.

Suggested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Originally-from: James Yang <james.yang@arm.com>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Kim Phillips <kim.phillips@arm.com>
Link: http://lkml.kernel.org/r/20171127042101.3659-2-dave@stgolabs.net
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2017-11-30 14:02:05 -03:00
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
Arnaldo Carvalho de Melo b0ad8ea664 perf tools: Remove unused 'prefix' from builtin functions
We got it from the git sources but never used it for anything, with the
place where this would be somehow used remaining:

  static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
  {
	prefix = NULL;
	if (p->option & RUN_SETUP)
		prefix = NULL; /* setup_perf_directory(); */

Ditch it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-uw5swz05vol0qpr32c5lpvus@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2017-03-27 11:58:09 -03:00
Arnaldo Carvalho de Melo a0f213e14b perf bench futex: Fix build on musl + clang
When building with clang on a musl libc system, Alpine Linux, we end up
hitting a problem where memset() is used but its prototype is not
present, add it to avoid this:

  bench/futex-wake.c:99:3: error: implicitly declaring library function 'memset' with type 'void *(void *, int, unsigned long)'
        [-Werror,-Wimplicit-function-declaration]
                  CPU_ZERO(&cpu);
                  ^
  /usr/include/sched.h:127:23: note: expanded from macro 'CPU_ZERO'
  #define CPU_ZERO(set) CPU_ZERO_S(sizeof(cpu_set_t),set)
                        ^
  /usr/include/sched.h:110:30: note: expanded from macro 'CPU_ZERO_S'
  #define CPU_ZERO_S(size,set) memset(set,0,size)
                               ^
  bench/futex-wake.c:99:3: note: include the header <string.h> or explicitly provide a declaration for 'memset'

Found while updating my test build containers to build perf with clang in more
systems.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-jh10vaz2r98zl6gm5iau8prr@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2017-03-03 19:07:19 -03:00
Arnaldo Carvalho de Melo 16cab3226f Revert "perf bench futex: Sanitize numeric parameters"
This reverts commit 60758d6668.

Now that libsubcmd makes sure that OPT_UINTEGER options will not
return negative values, we can revert this patch while addressing
the problem it solved:

  # perf bench futex hash -t  -4
  # Running 'futex/hash' benchmark:
   Error: switch `t' expects an unsigned numerical value
   Usage: perf bench futex hash <options>

      -t, --threads <n>     Specify amount of threads
  # perf bench futex hash -t-4
  # Running 'futex/hash' benchmark:
   Error: switch `t' expects an unsigned numerical value
   Usage: perf bench futex hash <options>

      -t, --threads <n>     Specify amount of threads
  #

IMO it is more reasonable to flat out refuse to process a negative
number than to silently turn it into an absolute value.

This also helps in silencing clang's complaint about asking for an
absolute value of an unsigned integer:

  bench/futex-hash.c:133:10: error: taking the absolute value of unsigned type 'unsigned int' has no effect [-Werror,-Wabsolute-value]
          nsecs = futexbench_sanitize_numeric(nsecs);
                ^
  bench/futex.h:104:42: note: expanded from macro 'futexbench_sanitize_numeric'
  #define futexbench_sanitize_numeric(__n) abs((__n))
                                           ^
  bench/futex-hash.c:133:10: note: remove the call to 'abs' since unsigned values cannot be negative

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-2kl68v22or31vw643m2exz8x@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2017-02-14 15:19:17 -03:00
Davidlohr Bueso 60758d6668 perf bench futex: Sanitize numeric parameters
This gets rid of oddities such as:

  perf bench futex hash -t -4
  perf: calloc: Cannot allocate memory

Runtime (and many more) are equally busted, i.e. run for bogus amounts of
time. Just use the abs, instead of, for example errorring out.

Committer note:

After the patch:

  $ perf bench futex hash -t -4
  # Running 'futex/hash' benchmark:
  Run summary [PID 10178]: 4 threads, each operating on 1024 [private] futexes for 10 secs.

  [thread  0] futexes: 0x34f9fa0 ... 0x34faf9c [ 4702208 ops/sec ]
  [thread  1] futexes: 0x34fb140 ... 0x34fc13c [ 4707020 ops/sec ]
  [thread  2] futexes: 0x34fc2e0 ... 0x34fd2dc [ 4711526 ops/sec ]
  [thread  3] futexes: 0x34fd480 ... 0x34fe47c [ 4709683 ops/sec ]

  Averaged 4707609 operations/sec (+- 0.04%), total secs = 10
  $

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lkml.kernel.org/r/1477342613-9938-3-git-send-email-dave@stgolabs.net
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-10-25 09:50:53 -03:00
Arnaldo Carvalho de Melo 565e69114e perf bench futex: Use NSEC_PER_USEC
Following kernel practices and better documentin

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-xncwqxegjp13g2nxih3lp9mx@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-08-23 15:37:33 -03:00
Arnaldo Carvalho de Melo 86695f59c9 perf bench futex: Add missing compiler.h header
Since these files use __maybe_unused, and that is defined in
linux/compiler.h, include it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-1llbf59ut6xon6ti88jm0n9j@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-12 15:20:30 -03:00
Arnaldo Carvalho de Melo 9c304f6c71 perf bench: Disentangle headers
We should try avoiding that perf.h header, it includes way too much
stuff, making it difficult to use things like setting _GNU_SOURCE only
on a small set of headers.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-lb6eg9w1kzrwhv0gm3ho0h54@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-12 15:19:54 -03:00
Arnaldo Carvalho de Melo 8a15858904 perf bench: Add missing pthread.h include for CPU_*() macros
Cc: David Ahern <dsahern@gmail.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-48qbfv7tqs8n8ey74lbyfjtq@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-12 15:19:52 -03:00
Josh Poimboeuf 4b6ab94eab perf subcmd: Create subcmd library
Move the subcommand-related files from perf to a new library named
libsubcmd.a.

Since we're moving files anyway, go ahead and rename 'exec_cmd.*' to
'exec-cmd.*' to be consistent with the naming of all the other files.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/c0a838d4c878ab17fee50998811612b2281355c1.1450193761.git.jpoimboe@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2015-12-17 14:27:14 -03:00
Davidlohr Bueso 052b0f6eaf perf bench futex: Fix hung wakeup tasks after requeueing
The futex-requeue benchmark can hang because of missing wakeups once the
benchmark is done, ie:

[Run 1]: Requeued 1024 of 1024 threads in 0.3290 ms
perf: couldn't wakeup all tasks (135/1024)

This bug, while perhaps suggesting missing wakeups in kernel futex code,
is merely a consequence of the crappy FUTEX_CMP_REQUEUE man page,
incorrectly mentioning that the number of requeued tasks is in fact
returned, not the wakeups.

This patch acknowledges this and updates the corresponding futex_wake
code around it.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Mel Gorman <mgorman@suse.de>
Link: http://lkml.kernel.org/r/1429894848.10273.44.camel@stgolabs.net
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2015-04-27 13:57:49 -03:00
Davidlohr Bueso e19685ed24 perf bench futex: Sanitize -q option in requeue
When given the number of threads to requeue at once by user input,
there's always the risk of this value being larger than the total number
of threads.  This doesn't make any sense, and the kernel can easily deal
with such sort of situations, hence no big deal. We should however
prevent bogus output such as:

./perf bench --repeat 2 futex requeue -q 10
Run summary [PID 22210]: Requeuing 4 threads (from [private] 0x99ef3c to 0x99ef38), 10 at a time.

[Run 1]: Requeued 10 of 4 threads in 0.0040 ms
[Run 2]: Requeued 10 of 4 threads in 0.0030 ms
Requeued 10 of 4 threads in 0.0035 ms (+-14.29%)

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Davidlohr Bueso <dbueso@suse.de>
Link: http://lkml.kernel.org/r/1412008868-22328-2-git-send-email-dave@stgolabs.net
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2014-09-29 15:43:26 -03:00
Davidlohr Bueso 86c87e13f8 perf bench futex: Support operations for shared futexes
Unlike futex-hash, requeuing and wakeup benchmarks do not support shared
futexes, limiting the usefulness of the programs. Correct this, and
allow using the local -S parameter. The default remains using private
futexes.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Davidlohr Bueso <dbueso@suse.de>
Link: http://lkml.kernel.org/r/1412008868-22328-1-git-send-email-dave@stgolabs.net
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2014-09-29 15:43:21 -03:00
Davidlohr Bueso d9de84afd1 perf bench futex: Use global --repeat option
This option is available through perf-bench, use it instead and free the
local option.

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/1402942467-10671-6-git-send-email-davidlohr@hp.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2014-06-19 16:13:16 -03:00
Davidlohr Bueso 0fb298cf95 perf bench: Add futex-requeue microbenchmark
Block a bunch of threads on a futex and requeue them on another, N at a
time.

This program is particularly useful to measure the latency of nthread
requeues without waking up any tasks -- thus mimicking a regular
futex_wait.

An example run:

  $ perf bench futex requeue -r 100 -t 64
  Run summary [PID 151011]: Requeuing 64 threads (from 0x7d15c4 to 0x7d15c8), 1 at a time.

  [Run 1]: Requeued 64 of 64 threads in 0.0400 ms
  [Run 2]: Requeued 64 of 64 threads in 0.0390 ms
  [Run 3]: Requeued 64 of 64 threads in 0.0400 ms
  ...
  [Run 100]: Requeued 64 of 64 threads in 0.0390 ms
  Requeued 64 of 64 threads in 0.0399 ms (+-0.37%)

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: Darren Hart <dvhart@linux.intel.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Darren Hart <dvhart@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <Waiman.Long@hp.com>
Link: http://lkml.kernel.org/r/1387081917-9102-4-git-send-email-davidlohr@hp.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2014-03-14 11:20:44 -03:00