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| author | Andi Kleen <ak@linux.intel.com> | 2019-11-21 01:15:11 +0100 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2019-11-28 12:08:38 +0100 |
| commit | d96645821e940bddff3fc5290656f83bf70d4c92 (patch) | |
| tree | 879409141d525cc6996d212afcfe5c01fe6d77be /tools/perf/util/fncache.h | |
| parent | perf regs: Make perf_reg_name() return "unknown" instead of NULL (diff) | |
| download | linux-d96645821e940bddff3fc5290656f83bf70d4c92.tar.xz linux-d96645821e940bddff3fc5290656f83bf70d4c92.zip | |
perf pmu: Use file system cache to optimize sysfs access
pmu.c does a lot of redundant /sys accesses while parsing aliases
and probing for PMUs. On large systems with a lot of PMUs this
can get expensive (>2s):
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
27.25 1.227847 8 160888 16976 openat
26.42 1.190481 7 164224 164077 stat
Add a cache to remember if specific file names exist or don't
exist, which eliminates most of this overhead.
Also optimize some stat() calls to be slightly cheaper access()
Resulting in:
0.18 0.004166 2 1851 305 open
0.08 0.001970 2 829 622 access
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20191121001522.180827-2-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/fncache.h')
| -rw-r--r-- | tools/perf/util/fncache.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/tools/perf/util/fncache.h b/tools/perf/util/fncache.h new file mode 100644 index 000000000000..fe020beaefb1 --- /dev/null +++ b/tools/perf/util/fncache.h @@ -0,0 +1,7 @@ +#ifndef _FCACHE_H +#define _FCACHE_H 1 + +unsigned shash(const unsigned char *s); +bool file_available(const char *name); + +#endif |