Messages in this thread | | | Date | Tue, 14 Feb 2012 20:08:42 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH 6/6 v4] memcg: fix performance of mem_cgroup_begin_update_page_stat() |
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On Mon, 13 Feb 2012 23:22:50 -0800 Greg Thelen <gthelen@google.com> wrote:
> On Mon, Feb 13, 2012 at 7:16 PM, KAMEZAWA Hiroyuki > <kamezawa.hiroyu@jp.fujitsu.com> wrote: > > From 3377fd7b6e23a5d2a368c078eae27e2b49c4f4aa Mon Sep 17 00:00:00 2001 > > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > > Date: Mon, 6 Feb 2012 12:14:47 +0900 > > Subject: [PATCH 6/6] memcg: fix performance of mem_cgroup_begin_update_page_stat() > > > > mem_cgroup_begin_update_page_stat() should be very fast because > > it's called very frequently. Now, it needs to look up page_cgroup > > and its memcg....this is slow. > > > > This patch adds a global variable to check "a memcg is moving or not". > > s/a memcg/any memcg/ > yes.
> > By this, the caller doesn't need to visit page_cgroup and memcg. > > s/By/With/ > ok.
> > Here is a test result. A test program makes page faults onto a file, > > MAP_SHARED and makes each page's page_mapcount(page) > 1, and free > > the range by madvise() and page fault again. This program causes > > 26214400 times of page fault onto a file(size was 1G.) and shows > > shows the cost of mem_cgroup_begin_update_page_stat(). > > Out of curiosity, what is the performance of the mmap program before > this series? >
Score of 3 runs underlinux-next. == [root@bluextal test]# time ./mmap 1G
real 0m21.041s user 0m6.146s sys 0m14.625s [root@bluextal test]# time ./mmap 1G
real 0m21.063s user 0m6.019s sys 0m14.776s [root@bluextal test]# time ./mmap 1G
real 0m21.178s user 0m6.000s sys 0m14.849s ==
My program is attached. This program is for checking cost of updating FILE_MAPPED. I guess sys_time scores's error rate will be 0.2-0.3 sec.
Thanks, -Kame == #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <sys/stat.h> #include <unistd.h> #include <sys/mman.h> #include <fcntl.h>
void reader(int fd, int size) { int i, off, x; char *addr;
addr = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0); for (i = 0; i < 100; i++) { for(off = 0; off < size; off += 4096) { x += *(addr + off); } madvise(addr, size, MADV_DONTNEED); } }
int main(int argc, char *argv[]) { int fd; char *addr, *c; unsigned long size; struct stat statbuf;
fd = open(argv[1], O_RDONLY); if (fd < 0) { perror("cannot open file"); return 1; }
if (fstat(fd, &statbuf)) { perror("fstat failed"); return 1; } size = statbuf.st_size; /* mmap in 2 place. */ addr = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0); mlock(addr, size); reader(fd, size); }
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