diff options
| author | Nelson Elhage <nelhage@nelhage.com> | 2011-12-19 08:39:32 -0500 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2011-12-23 16:53:58 -0200 |
| commit | 41d0d933494ce10eb77758a1168b08e317c42e8e (patch) | |
| tree | f907773714846b5b5cf85b4f450bb6fe07b168d4 /tools/perf/util/util.h | |
| parent | 18e6093904abfd51671ff5846c2fdaba9ebbf21b (diff) | |
| download | linux-3.10-41d0d933494ce10eb77758a1168b08e317c42e8e.tar.gz linux-3.10-41d0d933494ce10eb77758a1168b08e317c42e8e.tar.bz2 linux-3.10-41d0d933494ce10eb77758a1168b08e317c42e8e.zip | |
perf: builtin-record: Document and check that mmap_pages must be a power of two.
Now that we automatically point users at it, let's provide them some
guidance so that they hopefully don't just get mysterious EINVAL's
from the kernel.
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1324301972-22740-4-git-send-email-nelhage@nelhage.com
Signed-off-by: Nelson Elhage <nelhage@nelhage.com>
[ committer note: Made it work after 50a682c ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/util.h')
| -rw-r--r-- | tools/perf/util/util.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h index 0128906bac8..37be34dff79 100644 --- a/tools/perf/util/util.h +++ b/tools/perf/util/util.h @@ -245,4 +245,15 @@ int readn(int fd, void *buf, size_t size); #define _STR(x) #x #define STR(x) _STR(x) +/* + * Determine whether some value is a power of two, where zero is + * *not* considered a power of two. + */ + +static inline __attribute__((const)) +bool is_power_of_2(unsigned long n) +{ + return (n != 0 && ((n & (n - 1)) == 0)); +} + #endif |