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perf tools: Read the cache line size lazily

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It is not read as commonly as 'page_size', so it makes sense to read it
lazily, caching its value when it is first read.

Less files open unconditionally at startup.

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: https://lkml.kernel.org/n/tip-35xhrq91u94uc1djtclek1ie@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo
2018-05-17 15:03:05 -03:00
parent 6e1690c4c0
commit 9ac94e31ca
5 changed files with 25 additions and 17 deletions
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11
tools/perf/perf.c
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@@ -421,16 +421,6 @@ void pthread__unblock_sigwinch(void)
pthread_sigmask(SIG_UNBLOCK, &set, NULL);
}
#ifdef _SC_LEVEL1_DCACHE_LINESIZE
#define cache_line_size(cacheline_sizep) *cacheline_sizep = sysconf(_SC_LEVEL1_DCACHE_LINESIZE)
#else
static void cache_line_size(int *cacheline_sizep)
{
if (sysfs__read_int("devices/system/cpu/cpu0/cache/index0/coherency_line_size", cacheline_sizep))
pr_debug("cannot determine cache line size");
}
#endif
int main(int argc, const char **argv)
{
int err;
@@ -444,7 +434,6 @@ int main(int argc, const char **argv)
/* The page_size is placed in util object. */
page_size = sysconf(_SC_PAGE_SIZE);
cache_line_size(&cacheline_size);
if (sysctl__read_int("kernel/perf_event_max_stack", &value) == 0)
sysctl_perf_event_max_stack = value;