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| author | Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> | 2016-03-17 14:20:22 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-03-17 15:09:34 -0700 |
| commit | d9b2ddf8078f743729a054362ad96be076f224af (patch) | |
| tree | f9117a790718e1262dcd948534f30ebfb683be80 /tools/vm | |
| parent | 7f2bd006334291178bd2bce3e506d4c7a34a0643 (diff) | |
| download | linux-d9b2ddf8078f743729a054362ad96be076f224af.tar.gz | |
tools/vm/page-types.c: avoid memset() in walk_pfn() when count == 1
I found that page-types is very slow and my testing shows many timeout
errors. Here's an example with a simple program allocating 1000 thps.
$ time ./page-types -p $(pgrep -f test_alloc)
...
real 0m17.201s
user 0m16.889s
sys 0m0.312s
Most of time is spent in memset(). Currently memset() clears over whole
buffer for every walk_pfn() call, which is inefficient when walk_pfn()
is called from walk_vma(), because in that case walk_pfn() is called for
each pfn. So this patch limits the zero initialization only for the
first element.
$ time ./page-types.patched -p $(pgrep -f test_alloc)
...
real 0m0.182s
user 0m0.046s
sys 0m0.135s
Fixes: 954e95584579 ("tools/vm/page-types.c: add memory cgroup dumping and filtering")
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Suggested-by: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'tools/vm')
| -rw-r--r-- | tools/vm/page-types.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/tools/vm/page-types.c b/tools/vm/page-types.c index dab61c377f54..e92903fc7113 100644 --- a/tools/vm/page-types.c +++ b/tools/vm/page-types.c @@ -633,7 +633,15 @@ static void walk_pfn(unsigned long voffset, unsigned long pages; unsigned long i; - memset(cgi, 0, sizeof cgi); + /* + * kpagecgroup_read() reads only if kpagecgroup were opened, but + * /proc/kpagecgroup might even not exist, so it's better to fill + * them with zeros here. + */ + if (count == 1) + cgi[0] = 0; + else + memset(cgi, 0, sizeof cgi); while (count) { batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH); |