From 41d0d933494ce10eb77758a1168b08e317c42e8e Mon Sep 17 00:00:00 2001 From: Nelson Elhage Date: Mon, 19 Dec 2011 08:39:32 -0500 Subject: 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 Cc: Paul Mackerras Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1324301972-22740-4-git-send-email-nelhage@nelhage.com Signed-off-by: Nelson Elhage [ committer note: Made it work after 50a682c ] Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/util.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'tools/perf/util/util.h') diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h index 0128906bac88..37be34dff798 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 -- cgit v1.2.2