From d96645821e940bddff3fc5290656f83bf70d4c92 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 20 Nov 2019 16:15:11 -0800 Subject: 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 Acked-by: Jiri Olsa Link: http://lore.kernel.org/lkml/20191121001522.180827-2-andi@firstfloor.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/srccode.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) (limited to 'tools/perf/util/srccode.c') diff --git a/tools/perf/util/srccode.c b/tools/perf/util/srccode.c index d84ed8b6caaa..c29edaaca863 100644 --- a/tools/perf/util/srccode.c +++ b/tools/perf/util/srccode.c @@ -16,6 +16,7 @@ #include "srccode.h" #include "debug.h" #include // page_size +#include "fncache.h" #define MAXSRCCACHE (32*1024*1024) #define MAXSRCFILES 64 @@ -36,14 +37,6 @@ static LIST_HEAD(srcfile_list); static long map_total_sz; static int num_srcfiles; -static unsigned shash(unsigned char *s) -{ - unsigned h = 0; - while (*s) - h = 65599 * h + *s++; - return h ^ (h >> 16); -} - static int countlines(char *map, int maplen) { int numl; -- cgit v1.2.3