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  1. 17 Dec, 2018 27 commits
  3. 22 Nov, 2018 12 commits
    • Ingo Molnar's avatar
      Merge tag 'perf-core-for-mingo-4.21-20181122' of... · e8e94fce
      Ingo Molnar authored 
      Merge tag 'perf-core-for-mingo-4.21-20181122' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo:

- Start using BPF maps in 'perf trace' for filters in the augmented syscalls
  code, keeping the existing code for tracepoint filters so that we can switch
  back and forth while getting everything BPFied (Arnaldo Carvalho de Melo)

- Suppress potential format-truncation warning in the PMU code (Ben Hutchings)

- Introduce 'perf bench epoll', with "wait" and "ctl" benchmarks (Davidlohr Bueso)

- Fix slowness due to -ffunction-section, do it by sorting the maps by name, so
  avoiding the using rb_first/next to traverse all entries looking for a map name,
  that with --ffunction-section gets to thousands of maps (Eric Saint-Etienne)

- Separate jvmti cmlr check (Jiri Olsa)

- Allow using the stepping when figuring out which JSON files to use for a x86
  processor, so that Cascadelake server can be support, which has the same
  cpuid as some other processor, being different only in the stepping (Kan Liang)

- Share code and output format for uregs and iregs 'perf script' output (Milian Wolff)

- Use perf_evsel__is_clocki() for clock events in 'perf stat' (Ravi Bangoria)
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      e8e94fce
    • Kan Liang's avatar
      perf pmu: Move *_cpuid_str() weak functions to header.c · f4a0742b
      Kan Liang authored 
      The weak functions, strcmp_cpuid_str() and get_cpuid_str(), are defined
in pmu.c.

Most of the cpuid related functions, including *_cpuid_str()'s
declaration and platform specific definition, are in header.c/h.

To make the declaration and definition of all cpuid related functions in
a consistent place, move the weak functions to header.c.

There is no functional change.
Suggested-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarKan Liang <kan.liang@linux.intel.com>
Link: http://lkml.kernel.org/r/20181121164939.13482-1-kan.liang@linux.intel.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      f4a0742b
    • Eric Saint-Etienne's avatar
      perf symbols: Fix slowness due to -ffunction-section · 1e628569
      Eric Saint-Etienne authored 
      Perf can take minutes to parse an image when -ffunction-section is used.
This is especially true with the kernel image when it is compiled this
way, which is the arm64 default since the patcheset "Enable deadcode
elimination at link time".

Perf organize maps using a rbtree. Whenever perf finds a new symbols, it
first searches this rbtree for the map it belongs to, by strcmp()'aring
section names.  When it finds the map with the right name, it uses it to
add the symbol. With a usual image there aren't so many maps but when
using -ffunction-section there's basically one map per function.  With
the kernel image that's north of 40,000 maps. For most symbols perf has
to parses the entire rbtree to eventually create a new map and add it.
Consequently perf spends most of the time browsing a rbtree that keeps
getting larger.

This performance fix introduces a secondary rbtree that indexes maps
based on the section name.
Signed-off-by: default avatarEric Saint-Etienne <eric.saint.etienne@oracle.com>
Reviewed-by: default avatarDave Kleikamp <dave.kleikamp@oracle.com>
Reviewed-by: default avatarDavid Aldridge <david.aldridge@oracle.com>
Reviewed-by: default avatarRob Gardner <rob.gardner@oracle.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.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/1542822679-25591-1-git-send-email-eric.saint.etienne@oracle.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      1e628569
    • Jiri Olsa's avatar
      perf jvmti: Separate jvmti cmlr check · dd1d0044
      Jiri Olsa authored 
      The Compiled Method Load Record (cmlr) is JDK specific interface to
access JVM stack info. This makes the jvmti agent code not compile under
another jdk, which does not support that.

Separating jvmti cmlr check into special feature check, and adding
HAVE_JVMTI_CMLR macro to indicate that.

Mark cmlr code in jvmti/libjvmti.c with HAVE_JVMTI_CMLR, so we can
compile it on system without cmlr support.

This change makes the jvmti compile with java-1.8.0-ibm package. It's
without the line numbers support, but the rest works.

Adding NO_JVMTI_CMLR compile variable for testing.
Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ben Gainey <ben.gainey@arm.com>
Cc: Gustavo Luiz Duarte <gduarte@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20181121154341.21521-1-jolsa@kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      dd1d0044
    • Kan Liang's avatar
      perf vendor events: Add JSON metrics for Cascadelake server · ecd94f1b
      Kan Liang authored 
      Add JSON metrics (based on event list v1) for Cascadelake server
Signed-off-by: default avatarKan Liang <kan.liang@linux.intel.com>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/3ab97c73-c197-8555-1a35-b54636e667e6@linux.intel.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      ecd94f1b
    • Kan Liang's avatar
      perf vendor events: Add stepping in CPUID string for x86 · 3b54411a
      Kan Liang authored 
      The perf tools cannot find the proper event list for the Cascadelake
server.  Because the Cascadelake server and the Skylake server have the
same CPU model number, which are used by the perf tools to find the
event list.

The stepping for Skylake server is up to 4.

The stepping for Cascadelake server starts from 5.

The stepping can be used to distinguish between them.

The stepping is added in get_cpuid_str().

The stepping information for Skylake server is updated in mapfile.csv.

A x86 specific strcmp_cpuid_cmp() function is added to handle two CPUID
formats in mapfile.csv, "vendor-family-model-stepping" and
"vendor-family-model":

- If a cpuid-regular-expression from the mapfile.csv using the new
  stepping format, a cpuid-string generated on the machine must include
  stepping. Otherwise, it is a mismatch.

- If the cpuid-regular-expression using the old non-stepping format,
  the stepping in the cpuid-string will be ignored.

The script, using environment string "PERF_CPUID" without stepping on
Skylake server, will be broken. If so, users must fix their scripts.

Committer notes:

Fixed this build error on centos:6 and debian:7:

  arch/x86/util/header.c: In function 'is_full_cpuid':
  arch/x86/util/header.c:82:39: error: declaration of 'cpuid' shadows a global declaration [-Werror=shadow]
  arch/x86/util/header.c:12:1: error: shadowed declaration is here [-Werror=shadow]
  arch/x86/util/header.c: In function 'strcmp_cpuid_str':
  arch/x86/util/header.c:98:56: error: declaration of 'cpuid' shadows a global declaration [-Werror=shadow]
  arch/x86/util/header.c:12:1: error: shadowed declaration is here [-Werror=shadow]
  cc1: all warnings being treated as errors
Signed-off-by: default avatarKan Liang <kan.liang@linux.intel.com>
Reviewed-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20181114212416.15665-1-kan.liang@linux.intel.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      3b54411a
    • Ravi Bangoria's avatar
      perf stat: Use perf_evsel__is_clocki() for clock events · eb08d006
      Ravi Bangoria authored 
      We already have function to check if a given event is either
SW_CPU_CLOCK or SW_TASK_CLOCK. Utilize it.
Signed-off-by: default avatarRavi Bangoria <ravi.bangoria@linux.ibm.com>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: yuzhoujian@didichuxing.com
Link: http://lkml.kernel.org/r/20181115095533.16930-1-ravi.bangoria@linux.ibm.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      eb08d006
    • Ben Hutchings's avatar
      perf pmu: Suppress potential format-truncation warning · 11a64a05
      Ben Hutchings authored 
      Depending on which functions are inlined in util/pmu.c, the snprintf()
calls in perf_pmu__parse_{scale,unit,per_pkg,snapshot}() might trigger a
warning:

  util/pmu.c: In function 'pmu_aliases':
  util/pmu.c:178:31: error: '%s' directive output may be truncated writing up to 255 bytes into a region of size between 0 and 4095 [-Werror=format-truncation=]
    snprintf(path, PATH_MAX, "%s/%s.unit", dir, name);
                               ^~

I found this when trying to build perf from Linux 3.16 with gcc 8.
However I can reproduce the problem in mainline if I force
__perf_pmu__new_alias() to be inlined.

Suppress this by using scnprintf() as has been done elsewhere in perf.
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20181111184524.fux4taownc6ndbx6@decadent.org.ukSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      11a64a05
    • Pu Wen's avatar
      perf tools: Add Hygon Dhyana support · 4787eff3
      Pu Wen authored 
      The tool perf is useful for the performance analysis on the Hygon Dhyana
platform. But right now there is no Hygon support for it to analyze the
KVM guest os data. So add Hygon Dhyana support to it by checking vendor
string to share the code path of AMD.
Signed-off-by: default avatarPu Wen <puwen@hygon.cn>
Acked-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1542008451-31735-1-git-send-email-puwen@hygon.cnSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      4787eff3
    • Davidlohr Bueso's avatar
      perf bench: Add epoll_ctl(2) benchmark · 231457ec
      Davidlohr Bueso authored 
      Benchmark the various operations allowed for epoll_ctl(2).  The idea is
to concurrently stress a single epoll instance doing add/mod/del
operations.

Committer testing:

  # perf bench epoll ctl
  # Running 'epoll/ctl' benchmark:
  Run summary [PID 20344]: 4 threads doing epoll_ctl ops 64 file-descriptors for 8 secs.

  [thread  0] fdmap: 0x21a46b0 ... 0x21a47ac [ add: 1680960 ops; mod: 1680960 ops; del: 1680960 ops ]
  [thread  1] fdmap: 0x21a4960 ... 0x21a4a5c [ add: 1685440 ops; mod: 1685440 ops; del: 1685440 ops ]
  [thread  2] fdmap: 0x21a4c10 ... 0x21a4d0c [ add: 1674368 ops; mod: 1674368 ops; del: 1674368 ops ]
  [thread  3] fdmap: 0x21a4ec0 ... 0x21a4fbc [ add: 1677568 ops; mod: 1677568 ops; del: 1677568 ops ]

  Averaged 1679584 ADD operations (+- 0.14%)
  Averaged 1679584 MOD operations (+- 0.14%)
  Averaged 1679584 DEL operations (+- 0.14%)
  #

Lets measure those calls with 'perf trace' to get a glympse at what this
benchmark is doing in terms of syscalls:

  # perf trace -m32768 -s perf bench epoll ctl
  # Running 'epoll/ctl' benchmark:
  Run summary [PID 20405]: 4 threads doing epoll_ctl ops 64 file-descriptors for 8 secs.

  [thread  0] fdmap: 0x21764e0 ... 0x21765dc [ add: 1100480 ops; mod: 1100480 ops; del: 1100480 ops ]
  [thread  1] fdmap: 0x2176790 ... 0x217688c [ add: 1250176 ops; mod: 1250176 ops; del: 1250176 ops ]
  [thread  2] fdmap: 0x2176a40 ... 0x2176b3c [ add: 1022464 ops; mod: 1022464 ops; del: 1022464 ops ]
  [thread  3] fdmap: 0x2176cf0 ... 0x2176dec [ add: 705472 ops; mod: 705472 ops; del: 705472 ops ]

  Averaged 1019648 ADD operations (+- 11.27%)
  Averaged 1019648 MOD operations (+- 11.27%)
  Averaged 1019648 DEL operations (+- 11.27%)

  Summary of events:

  epoll-ctl (20405), 1264 events, 0.0%

   syscall            calls    total       min       avg       max      stddev
                               (msec)    (msec)    (msec)    (msec)        (%)
   --------------- -------- --------- --------- --------- ---------     ------
   eventfd2             256     9.514     0.001     0.037     5.243     68.00%
   clone                  4     1.245     0.204     0.311     0.531     24.13%
   mprotect              66     0.345     0.002     0.005     0.021      7.43%
   openat                45     0.313     0.004     0.007     0.073     21.93%
   mmap                  88     0.302     0.002     0.003     0.013      5.02%
   futex                  4     0.160     0.002     0.040     0.140     83.43%
   sched_setaffinity      4     0.124     0.005     0.031     0.070     49.39%
   read                  44     0.103     0.001     0.002     0.013     15.54%
   fstat                 40     0.052     0.001     0.001     0.003      5.43%
   close                 39     0.039     0.001     0.001     0.001      1.48%
   stat                   9     0.034     0.003     0.004     0.006      7.30%
   access                 3     0.023     0.007     0.008     0.008      4.25%
   open                   2     0.021     0.008     0.011     0.013     22.60%
   getdents               4     0.019     0.001     0.005     0.009     37.15%
   write                  2     0.013     0.004     0.007     0.009     38.48%
   munmap                 1     0.010     0.010     0.010     0.010      0.00%
   brk                    3     0.006     0.001     0.002     0.003     26.34%
   rt_sigprocmask         2     0.004     0.001     0.002     0.003     43.95%
   rt_sigaction           3     0.004     0.001     0.001     0.002     16.07%
   prlimit64              3     0.004     0.001     0.001     0.001      5.39%
   prctl                  1     0.003     0.003     0.003     0.003      0.00%
   epoll_create           1     0.003     0.003     0.003     0.003      0.00%
   lseek                  2     0.002     0.001     0.001     0.001     11.42%
   sched_getaffinity        1     0.002     0.002     0.002     0.002      0.00%
   arch_prctl             1     0.002     0.002     0.002     0.002      0.00%
   set_tid_address        1     0.001     0.001     0.001     0.001      0.00%
   getpid                 1     0.001     0.001     0.001     0.001      0.00%
   set_robust_list        1     0.001     0.001     0.001     0.001      0.00%
   execve                 1     0.000     0.000     0.000     0.000      0.00%

 epoll-ctl (20406), 1245480 events, 14.6%

   syscall            calls    total       min       avg       max      stddev
                               (msec)    (msec)    (msec)    (msec)        (%)
   --------------- -------- --------- --------- --------- ---------     ------
   epoll_ctl         619511  1034.927     0.001     0.002     6.691      0.67%
   nanosleep           3226   616.114     0.006     0.191    10.376      7.57%
   futex                  2    11.336     0.002     5.668    11.334     99.97%
   set_robust_list        1     0.001     0.001     0.001     0.001      0.00%
   clone                  1     0.000     0.000     0.000     0.000      0.00%

 epoll-ctl (20407), 1243151 events, 14.5%

   syscall            calls    total       min       avg       max      stddev
                               (msec)    (msec)    (msec)    (msec)        (%)
   --------------- -------- --------- --------- --------- ---------     ------
   epoll_ctl         618350  1042.181     0.001     0.002     2.512      0.40%
   nanosleep           3220   366.261     0.012     0.114    18.162      9.59%
   futex                  4     5.463     0.001     1.366     5.427     99.12%
   set_robust_list        1     0.002     0.002     0.002     0.002      0.00%

 epoll-ctl (20408), 1801690 events, 21.1%

   syscall            calls    total       min       avg       max      stddev
                               (msec)    (msec)    (msec)    (msec)        (%)
   --------------- -------- --------- --------- --------- ---------     ------
   epoll_ctl         896174  1540.581     0.001     0.002     6.987      0.74%
   nanosleep           4667   783.393     0.006     0.168    10.419      7.10%
   futex                  2     4.682     0.002     2.341     4.681     99.93%
   set_robust_list        1     0.002     0.002     0.002     0.002      0.00%
   clone                  1     0.000     0.000     0.000     0.000      0.00%

 epoll-ctl (20409), 4254890 events, 49.8%

   syscall            calls    total       min       avg       max      stddev
                               (msec)    (msec)    (msec)    (msec)        (%)
   --------------- -------- --------- --------- --------- ---------     ------
   epoll_ctl        2116416  3768.097     0.001     0.002     9.956      0.41%
   nanosleep          11023  1141.778     0.006     0.104     9.447      4.95%
   futex                  3     0.037     0.002     0.012     0.029     70.50%
   set_robust_list        1     0.008     0.008     0.008     0.008      0.00%
   madvise                1     0.005     0.005     0.005     0.005      0.00%
   clone                  1     0.000     0.000     0.000     0.000      0.00%
  #

Committer notes:

Fix build on fedora:24-x-ARC-uClibc, debian:experimental-x-mips,
debian:experimental-x-mipsel, ubuntu:16.04-x-arm and ubuntu:16.04-x-powerpc

    CC       /tmp/build/perf/bench/epoll-ctl.o
  bench/epoll-ctl.c: In function 'init_fdmaps':
  bench/epoll-ctl.c:214:16: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
    for (i = 0; i < nfds; i+=inc) {
                  ^
  bench/epoll-ctl.c: In function 'bench_epoll_ctl':
  bench/epoll-ctl.c:377:16: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
    for (i = 0; i < nthreads; i++) {
                  ^
  bench/epoll-ctl.c:388:16: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
    for (i = 0; i < nthreads; i++) {
                  ^
  cc1: all warnings being treated as errors
Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Link: http://lkml.kernel.org/r/20181106152226.20883-3-dave@stgolabs.net
[ Use inttypes.h to print rlim_t fields, fixing the build on Alpine Linux / musl libc ]
[ Check if eventfd() is available, i.e. if HAVE_EVENTFD is defined ]
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      231457ec
    • Davidlohr Bueso's avatar
      perf bench: Add epoll parallel epoll_wait benchmark · 121dd9ea
      Davidlohr Bueso authored 
      This program benchmarks concurrent epoll_wait(2) for file descriptors
that are monitored with with EPOLLIN along various semantics, by a
single epoll instance. Such conditions can be found when using
single/combined or multiple queuing when load balancing.

Each thread has a number of private, nonblocking file descriptors,
referred to as fdmap. A writer thread will constantly be writing to the
fdmaps of all threads, minimizing each threads's chances of epoll_wait
not finding any ready read events and blocking as this is not what we
want to stress. Full details in the start of the C file.

Committer testing:

  # perf bench
  Usage:
	perf bench [<common options>] <collection> <benchmark> [<options>]

        # List of all available benchmark collections:

         sched: Scheduler and IPC benchmarks
           mem: Memory access benchmarks
          numa: NUMA scheduling and MM benchmarks
         futex: Futex stressing benchmarks
         epoll: Epoll stressing benchmarks
           all: All benchmarks

  # perf bench epoll

        # List of available benchmarks for collection 'epoll':

          wait: Benchmark epoll concurrent epoll_waits
           all: Run all futex benchmarks

  # perf bench epoll wait
  # Running 'epoll/wait' benchmark:
  Run summary [PID 19295]: 3 threads monitoring on 64 file-descriptors for 8 secs.

  [thread  0] fdmap: 0xdaa650 ... 0xdaa74c [ 328241 ops/sec ]
  [thread  1] fdmap: 0xdaa900 ... 0xdaa9fc [ 351695 ops/sec ]
  [thread  2] fdmap: 0xdaabb0 ... 0xdaacac [ 381423 ops/sec ]

  Averaged 353786 operations/sec (+- 4.35%), total secs = 8
  #

Committer notes:

Fix the build on debian:experimental-x-mips, debian:experimental-x-mipsel
and others:

    CC       /tmp/build/perf/bench/epoll-wait.o
  bench/epoll-wait.c: In function 'writerfn':
  bench/epoll-wait.c:399:12: error: format '%ld' expects argument of type 'long int', but argument 2 has type 'size_t' {aka 'unsigned int'} [-Werror=format=]
    printinfo("exiting writer-thread (total full-loops: %ld)\n", iter);
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  ~~~~
  bench/epoll-wait.c:86:31: note: in definition of macro 'printinfo'
    do { if (__verbose) { printf(fmt, ## arg); fflush(stdout); } } while (0)
                                 ^~~
  cc1: all warnings being treated as errors
Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Jason Baron <jbaron@akamai.com> <jbaron@akamai.com>
Link: http://lkml.kernel.org/r/20181106152226.20883-2-dave@stgolabs.net
Link: http://lkml.kernel.org/r/20181106182349.thdkpvshkna5vd7o@linux-r8p5>
[ Applied above fixup as per Davidlohr's request ]
[ Use inttypes.h to print rlim_t fields, fixing the build on Alpine Linux / musl libc ]
[ Check if eventfd() is available, i.e. if HAVE_EVENTFD is defined ]
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      121dd9ea
    • Arnaldo Carvalho de Melo's avatar
      tools build feature: Check if eventfd() is available · 11c6cbe7
      Arnaldo Carvalho de Melo authored 
      A new 'perf bench epoll' will use this, and to disable it for older
systems, add a feature test for this API.

This is just a simple program that if successfully compiled, means that
the feature is present, at least at the library level, in a build that
sets the output directory to /tmp/build/perf (using O=/tmp/build/perf),
we end up with:

  $ ls -la /tmp/build/perf/feature/test-eventfd*
  -rwxrwxr-x. 1 acme acme 8176 Nov 21 15:58 /tmp/build/perf/feature/test-eventfd.bin
  -rw-rw-r--. 1 acme acme  588 Nov 21 15:58 /tmp/build/perf/feature/test-eventfd.d
  -rw-rw-r--. 1 acme acme    0 Nov 21 15:58 /tmp/build/perf/feature/test-eventfd.make.output
  $ ldd /tmp/build/perf/feature/test-eventfd.bin
	  linux-vdso.so.1 (0x00007fff3bf3f000)
	  libc.so.6 => /lib64/libc.so.6 (0x00007fa984061000)
	  /lib64/ld-linux-x86-64.so.2 (0x00007fa984417000)
  $ grep eventfd -A 2 -B 2 /tmp/build/perf/FEATURE-DUMP
  feature-dwarf=1
  feature-dwarf_getlocations=1
  feature-eventfd=1
  feature-fortify-source=1
  feature-sync-compare-and-swap=1
  $

The main thing here is that in the end we'll have -DHAVE_EVENTFD in
CFLAGS, and then the 'perf bench' entry needing that API can be
selectively pruned.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-wkeldwob7dpx6jvtuzl8164k@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      11c6cbe7
  5. 21 Nov, 2018 1 commit
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