Re: [PATCH v1] tools/vm/page-types.c: remove memset() in walk_pfn()
On Wed, Mar 09, 2016 at 07:28:21AM +0300, Konstantin Khlebnikov wrote: > On Tue, Mar 8, 2016 at 8:58 AM, Naoya Horiguchi >wrote: > > On Tue, Mar 08, 2016 at 08:12:09AM +0300, Konstantin Khlebnikov wrote: > >> On Tue, Mar 8, 2016 at 4:47 AM, Naoya Horiguchi > >> wrote: > >> > 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) > >> > ... > >> > real0m17.201s > >> > user0m16.889s > >> > sys 0m0.312s > >> > > >> > $ time ./page-types.patched -p $(pgrep -f test_alloc) > >> > ... > >> > real0m0.182s > >> > user0m0.046s > >> > sys 0m0.135s > >> > > >> > Most of time is spent in memset(), which isn't necessary because we check > >> > that the return of kpagecgroup_read() is equal to pages and uninitialized > >> > memory is never used. So we can drop this memset(). > >> > >> These zeros are used in show_page_range() - for merging pages into ranges. > > > > Hi Konstantin, > > > > Thank you for the response. The below code does solve the problem, so > > that's fine. > > > > But I don't understand how the zeros are used. show_page_range() is called > > via add_page() which is called for i=0 to i=pages-1, and the buffer cgi is > > already filled for the range [i, pages-1] by kpagecgroup_read(), so even if > > without zero initialization, kpagecgroup_read() properly fills zeros, right? > > IOW, is there any problem if we don't do this zero initialization? > > kpagecgroup_read() reads only if kpagecgroup were opened, > /proc/kpagecgroup might even not exist. Probably it's better to fill > them with zeros here. > Pre-memset was an optimization - it fills buffer only once instead on > each kpagecgroup_read() call. Ah, OK. So here's ver.2. Thanks, Naoya --- From: Naoya Horiguchi Subject: [PATCH v2] 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) ... real0m17.201s user0m16.889s 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) ... real0m0.182s user0m0.046s sys 0m0.135s Fixes: 954e95584579 ("tools/vm/page-types.c: add memory cgroup dumping and filtering") Signed-off-by: Naoya Horiguchi Suggested-by: Konstantin Khlebnikov --- tools/vm/page-types.c | 10 +- 1 file changed, 9 insertions(+), 1 deletion(-) 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); -- 2.4.3
Re: [PATCH v1] tools/vm/page-types.c: remove memset() in walk_pfn()
On Wed, Mar 09, 2016 at 07:28:21AM +0300, Konstantin Khlebnikov wrote: > On Tue, Mar 8, 2016 at 8:58 AM, Naoya Horiguchi > wrote: > > On Tue, Mar 08, 2016 at 08:12:09AM +0300, Konstantin Khlebnikov wrote: > >> On Tue, Mar 8, 2016 at 4:47 AM, Naoya Horiguchi > >> wrote: > >> > 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) > >> > ... > >> > real0m17.201s > >> > user0m16.889s > >> > sys 0m0.312s > >> > > >> > $ time ./page-types.patched -p $(pgrep -f test_alloc) > >> > ... > >> > real0m0.182s > >> > user0m0.046s > >> > sys 0m0.135s > >> > > >> > Most of time is spent in memset(), which isn't necessary because we check > >> > that the return of kpagecgroup_read() is equal to pages and uninitialized > >> > memory is never used. So we can drop this memset(). > >> > >> These zeros are used in show_page_range() - for merging pages into ranges. > > > > Hi Konstantin, > > > > Thank you for the response. The below code does solve the problem, so > > that's fine. > > > > But I don't understand how the zeros are used. show_page_range() is called > > via add_page() which is called for i=0 to i=pages-1, and the buffer cgi is > > already filled for the range [i, pages-1] by kpagecgroup_read(), so even if > > without zero initialization, kpagecgroup_read() properly fills zeros, right? > > IOW, is there any problem if we don't do this zero initialization? > > kpagecgroup_read() reads only if kpagecgroup were opened, > /proc/kpagecgroup might even not exist. Probably it's better to fill > them with zeros here. > Pre-memset was an optimization - it fills buffer only once instead on > each kpagecgroup_read() call. Ah, OK. So here's ver.2. Thanks, Naoya --- From: Naoya Horiguchi Subject: [PATCH v2] 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) ... real0m17.201s user0m16.889s 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) ... real0m0.182s user0m0.046s sys 0m0.135s Fixes: 954e95584579 ("tools/vm/page-types.c: add memory cgroup dumping and filtering") Signed-off-by: Naoya Horiguchi Suggested-by: Konstantin Khlebnikov --- tools/vm/page-types.c | 10 +- 1 file changed, 9 insertions(+), 1 deletion(-) 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); -- 2.4.3
Re: [PATCH v1] tools/vm/page-types.c: remove memset() in walk_pfn()
On Tue, Mar 8, 2016 at 8:58 AM, Naoya Horiguchiwrote: > On Tue, Mar 08, 2016 at 08:12:09AM +0300, Konstantin Khlebnikov wrote: >> On Tue, Mar 8, 2016 at 4:47 AM, Naoya Horiguchi >> wrote: >> > 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) >> > ... >> > real0m17.201s >> > user0m16.889s >> > sys 0m0.312s >> > >> > $ time ./page-types.patched -p $(pgrep -f test_alloc) >> > ... >> > real0m0.182s >> > user0m0.046s >> > sys 0m0.135s >> > >> > Most of time is spent in memset(), which isn't necessary because we check >> > that the return of kpagecgroup_read() is equal to pages and uninitialized >> > memory is never used. So we can drop this memset(). >> >> These zeros are used in show_page_range() - for merging pages into ranges. > > Hi Konstantin, > > Thank you for the response. The below code does solve the problem, so that's > fine. > > But I don't understand how the zeros are used. show_page_range() is called > via add_page() which is called for i=0 to i=pages-1, and the buffer cgi is > already filled for the range [i, pages-1] by kpagecgroup_read(), so even if > without zero initialization, kpagecgroup_read() properly fills zeros, right? > IOW, is there any problem if we don't do this zero initialization? kpagecgroup_read() reads only if kpagecgroup were opened, /proc/kpagecgroup might even not exist. Probably it's better to fill them with zeros here. Pre-memset was an optimization - it fills buffer only once instead on each kpagecgroup_read() call. > > Thanks, > Naoya Horiguchi > >> You could add fast-path for count=1 >> >> @@ -633,7 +633,10 @@ static void walk_pfn(unsigned long voffset, >> unsigned long pages; >> unsigned long i; >> >> - memset(cgi, 0, sizeof cgi); >> + if (count == 1) >> + cgi[0] = 0; >> + else >> + memset(cgi, 0, sizeof cgi); >> >> while (count) { >> batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH); >>
Re: [PATCH v1] tools/vm/page-types.c: remove memset() in walk_pfn()
On Tue, Mar 8, 2016 at 8:58 AM, Naoya Horiguchi wrote: > On Tue, Mar 08, 2016 at 08:12:09AM +0300, Konstantin Khlebnikov wrote: >> On Tue, Mar 8, 2016 at 4:47 AM, Naoya Horiguchi >> wrote: >> > 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) >> > ... >> > real0m17.201s >> > user0m16.889s >> > sys 0m0.312s >> > >> > $ time ./page-types.patched -p $(pgrep -f test_alloc) >> > ... >> > real0m0.182s >> > user0m0.046s >> > sys 0m0.135s >> > >> > Most of time is spent in memset(), which isn't necessary because we check >> > that the return of kpagecgroup_read() is equal to pages and uninitialized >> > memory is never used. So we can drop this memset(). >> >> These zeros are used in show_page_range() - for merging pages into ranges. > > Hi Konstantin, > > Thank you for the response. The below code does solve the problem, so that's > fine. > > But I don't understand how the zeros are used. show_page_range() is called > via add_page() which is called for i=0 to i=pages-1, and the buffer cgi is > already filled for the range [i, pages-1] by kpagecgroup_read(), so even if > without zero initialization, kpagecgroup_read() properly fills zeros, right? > IOW, is there any problem if we don't do this zero initialization? kpagecgroup_read() reads only if kpagecgroup were opened, /proc/kpagecgroup might even not exist. Probably it's better to fill them with zeros here. Pre-memset was an optimization - it fills buffer only once instead on each kpagecgroup_read() call. > > Thanks, > Naoya Horiguchi > >> You could add fast-path for count=1 >> >> @@ -633,7 +633,10 @@ static void walk_pfn(unsigned long voffset, >> unsigned long pages; >> unsigned long i; >> >> - memset(cgi, 0, sizeof cgi); >> + if (count == 1) >> + cgi[0] = 0; >> + else >> + memset(cgi, 0, sizeof cgi); >> >> while (count) { >> batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH); >>
Re: [PATCH v1] tools/vm/page-types.c: remove memset() in walk_pfn()
On Tue, Mar 08, 2016 at 08:12:09AM +0300, Konstantin Khlebnikov wrote: > On Tue, Mar 8, 2016 at 4:47 AM, Naoya Horiguchi >wrote: > > 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) > > ... > > real0m17.201s > > user0m16.889s > > sys 0m0.312s > > > > $ time ./page-types.patched -p $(pgrep -f test_alloc) > > ... > > real0m0.182s > > user0m0.046s > > sys 0m0.135s > > > > Most of time is spent in memset(), which isn't necessary because we check > > that the return of kpagecgroup_read() is equal to pages and uninitialized > > memory is never used. So we can drop this memset(). > > These zeros are used in show_page_range() - for merging pages into ranges. Hi Konstantin, Thank you for the response. The below code does solve the problem, so that's fine. But I don't understand how the zeros are used. show_page_range() is called via add_page() which is called for i=0 to i=pages-1, and the buffer cgi is already filled for the range [i, pages-1] by kpagecgroup_read(), so even if without zero initialization, kpagecgroup_read() properly fills zeros, right? IOW, is there any problem if we don't do this zero initialization? Thanks, Naoya Horiguchi > You could add fast-path for count=1 > > @@ -633,7 +633,10 @@ static void walk_pfn(unsigned long voffset, > unsigned long pages; > unsigned long i; > > - memset(cgi, 0, sizeof cgi); > + if (count == 1) > + cgi[0] = 0; > + else > + memset(cgi, 0, sizeof cgi); > > while (count) { > batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH); >
Re: [PATCH v1] tools/vm/page-types.c: remove memset() in walk_pfn()
On Tue, Mar 08, 2016 at 08:12:09AM +0300, Konstantin Khlebnikov wrote: > On Tue, Mar 8, 2016 at 4:47 AM, Naoya Horiguchi > wrote: > > 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) > > ... > > real0m17.201s > > user0m16.889s > > sys 0m0.312s > > > > $ time ./page-types.patched -p $(pgrep -f test_alloc) > > ... > > real0m0.182s > > user0m0.046s > > sys 0m0.135s > > > > Most of time is spent in memset(), which isn't necessary because we check > > that the return of kpagecgroup_read() is equal to pages and uninitialized > > memory is never used. So we can drop this memset(). > > These zeros are used in show_page_range() - for merging pages into ranges. Hi Konstantin, Thank you for the response. The below code does solve the problem, so that's fine. But I don't understand how the zeros are used. show_page_range() is called via add_page() which is called for i=0 to i=pages-1, and the buffer cgi is already filled for the range [i, pages-1] by kpagecgroup_read(), so even if without zero initialization, kpagecgroup_read() properly fills zeros, right? IOW, is there any problem if we don't do this zero initialization? Thanks, Naoya Horiguchi > You could add fast-path for count=1 > > @@ -633,7 +633,10 @@ static void walk_pfn(unsigned long voffset, > unsigned long pages; > unsigned long i; > > - memset(cgi, 0, sizeof cgi); > + if (count == 1) > + cgi[0] = 0; > + else > + memset(cgi, 0, sizeof cgi); > > while (count) { > batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH); >
Re: [PATCH v1] tools/vm/page-types.c: remove memset() in walk_pfn()
On Tue, Mar 8, 2016 at 4:47 AM, Naoya Horiguchiwrote: > 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) > ... > real0m17.201s > user0m16.889s > sys 0m0.312s > > $ time ./page-types.patched -p $(pgrep -f test_alloc) > ... > real0m0.182s > user0m0.046s > sys 0m0.135s > > Most of time is spent in memset(), which isn't necessary because we check > that the return of kpagecgroup_read() is equal to pages and uninitialized > memory is never used. So we can drop this memset(). These zeros are used in show_page_range() - for merging pages into ranges. You could add fast-path for count=1 @@ -633,7 +633,10 @@ static void walk_pfn(unsigned long voffset, unsigned long pages; unsigned long i; - memset(cgi, 0, sizeof cgi); + if (count == 1) + cgi[0] = 0; + else + memset(cgi, 0, sizeof cgi); while (count) { batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH); > > Fixes: 954e95584579 ("tools/vm/page-types.c: add memory cgroup dumping and > filtering") > Signed-off-by: Naoya Horiguchi > --- > tools/vm/page-types.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git v4.5-rc5-mmotm-2016-02-24-16-18/tools/vm/page-types.c > v4.5-rc5-mmotm-2016-02-24-16-18_patched/tools/vm/page-types.c > index dab61c3..c192baf 100644 > --- v4.5-rc5-mmotm-2016-02-24-16-18/tools/vm/page-types.c > +++ v4.5-rc5-mmotm-2016-02-24-16-18_patched/tools/vm/page-types.c > @@ -633,8 +633,6 @@ static void walk_pfn(unsigned long voffset, > unsigned long pages; > unsigned long i; > > - memset(cgi, 0, sizeof cgi); > - > while (count) { > batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH); > pages = kpageflags_read(buf, index, batch); > -- > 2.7.0 >
Re: [PATCH v1] tools/vm/page-types.c: remove memset() in walk_pfn()
On Tue, Mar 8, 2016 at 4:47 AM, Naoya Horiguchi wrote: > 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) > ... > real0m17.201s > user0m16.889s > sys 0m0.312s > > $ time ./page-types.patched -p $(pgrep -f test_alloc) > ... > real0m0.182s > user0m0.046s > sys 0m0.135s > > Most of time is spent in memset(), which isn't necessary because we check > that the return of kpagecgroup_read() is equal to pages and uninitialized > memory is never used. So we can drop this memset(). These zeros are used in show_page_range() - for merging pages into ranges. You could add fast-path for count=1 @@ -633,7 +633,10 @@ static void walk_pfn(unsigned long voffset, unsigned long pages; unsigned long i; - memset(cgi, 0, sizeof cgi); + if (count == 1) + cgi[0] = 0; + else + memset(cgi, 0, sizeof cgi); while (count) { batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH); > > Fixes: 954e95584579 ("tools/vm/page-types.c: add memory cgroup dumping and > filtering") > Signed-off-by: Naoya Horiguchi > --- > tools/vm/page-types.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git v4.5-rc5-mmotm-2016-02-24-16-18/tools/vm/page-types.c > v4.5-rc5-mmotm-2016-02-24-16-18_patched/tools/vm/page-types.c > index dab61c3..c192baf 100644 > --- v4.5-rc5-mmotm-2016-02-24-16-18/tools/vm/page-types.c > +++ v4.5-rc5-mmotm-2016-02-24-16-18_patched/tools/vm/page-types.c > @@ -633,8 +633,6 @@ static void walk_pfn(unsigned long voffset, > unsigned long pages; > unsigned long i; > > - memset(cgi, 0, sizeof cgi); > - > while (count) { > batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH); > pages = kpageflags_read(buf, index, batch); > -- > 2.7.0 >
[PATCH v1] tools/vm/page-types.c: remove memset() in walk_pfn()
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) ... real0m17.201s user0m16.889s sys 0m0.312s $ time ./page-types.patched -p $(pgrep -f test_alloc) ... real0m0.182s user0m0.046s sys 0m0.135s Most of time is spent in memset(), which isn't necessary because we check that the return of kpagecgroup_read() is equal to pages and uninitialized memory is never used. So we can drop this memset(). Fixes: 954e95584579 ("tools/vm/page-types.c: add memory cgroup dumping and filtering") Signed-off-by: Naoya Horiguchi--- tools/vm/page-types.c | 2 -- 1 file changed, 2 deletions(-) diff --git v4.5-rc5-mmotm-2016-02-24-16-18/tools/vm/page-types.c v4.5-rc5-mmotm-2016-02-24-16-18_patched/tools/vm/page-types.c index dab61c3..c192baf 100644 --- v4.5-rc5-mmotm-2016-02-24-16-18/tools/vm/page-types.c +++ v4.5-rc5-mmotm-2016-02-24-16-18_patched/tools/vm/page-types.c @@ -633,8 +633,6 @@ static void walk_pfn(unsigned long voffset, unsigned long pages; unsigned long i; - memset(cgi, 0, sizeof cgi); - while (count) { batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH); pages = kpageflags_read(buf, index, batch); -- 2.7.0
[PATCH v1] tools/vm/page-types.c: remove memset() in walk_pfn()
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) ... real0m17.201s user0m16.889s sys 0m0.312s $ time ./page-types.patched -p $(pgrep -f test_alloc) ... real0m0.182s user0m0.046s sys 0m0.135s Most of time is spent in memset(), which isn't necessary because we check that the return of kpagecgroup_read() is equal to pages and uninitialized memory is never used. So we can drop this memset(). Fixes: 954e95584579 ("tools/vm/page-types.c: add memory cgroup dumping and filtering") Signed-off-by: Naoya Horiguchi --- tools/vm/page-types.c | 2 -- 1 file changed, 2 deletions(-) diff --git v4.5-rc5-mmotm-2016-02-24-16-18/tools/vm/page-types.c v4.5-rc5-mmotm-2016-02-24-16-18_patched/tools/vm/page-types.c index dab61c3..c192baf 100644 --- v4.5-rc5-mmotm-2016-02-24-16-18/tools/vm/page-types.c +++ v4.5-rc5-mmotm-2016-02-24-16-18_patched/tools/vm/page-types.c @@ -633,8 +633,6 @@ static void walk_pfn(unsigned long voffset, unsigned long pages; unsigned long i; - memset(cgi, 0, sizeof cgi); - while (count) { batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH); pages = kpageflags_read(buf, index, batch); -- 2.7.0