tools build feature: Check if eventfd() is available
authorArnaldo Carvalho de Melo <acme@redhat.com>
Wed, 21 Nov 2018 20:42:00 +0000 (17:42 -0300)
committerArnaldo Carvalho de Melo <acme@redhat.com>
Thu, 22 Nov 2018 01:25:44 +0000 (22:25 -0300)
commit11c6cbe706f218a8dc7e1f962f12b3a52ddd33a9
tree447b75de74aabf184590ef63aeae5773e96a39e0
parentd47d77c3f008d3cf02c6ce92ef4f6e32ca270351
tools build feature: Check if eventfd() is available

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.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
tools/build/Makefile.feature
tools/build/feature/Makefile
tools/build/feature/test-all.c
tools/build/feature/test-eventfd.c [new file with mode: 0644]
tools/perf/Makefile.config