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SubjectRe: [PATCH 0/6] page cgroup diet v5
On Fri, 17 Feb 2012 18:24:26 +0900
KAMEZAWA Hiroyuki <> wrote:

> This patch set is for removing 2 flags PCG_FILE_MAPPED and PCG_MOVE_LOCK on
> page_cgroup->flags. After this, page_cgroup has only 3bits of flags.
> And, this set introduces a new method to update page status accounting per memcg.
> With it, we don't have to add new flags onto page_cgroup if 'struct page' has
> information. This will be good for avoiding a new flag for page_cgroup.
> Fixed pointed out parts.
> - added more comments
> - fixed texts
> - removed redundant arguments.
> Passed some tests on 3.3.0-rc3-next-20120216.

Here is a micro benchmark test before/after this series.
mmap 1G bytes twice and repeat fault->drop repeatedly. (test program is attached)

== Before == 3 runs after 1st run
[root@bluextal test]# time ./mmap 1G

real 0m21.053s
user 0m6.046s
sys 0m14.743s
[root@bluextal test]# time ./mmap 1G

real 0m21.302s
user 0m6.027s
sys 0m14.979s
[root@bluextal test]# time ./mmap 1G

real 0m21.061s
user 0m6.020s
sys 0m14.722s

== After == 3 runs after 1st run
[root@bluextal test]# time ./mmap 1G

real 0m20.969s
user 0m5.960s
sys 0m14.777s
[root@bluextal test]# time ./mmap 1G

real 0m20.968s
user 0m6.069s
sys 0m14.650s
[root@bluextal test]# time ./mmap 1G

real 0m21.164s
user 0m6.152s
sys 0m14.707s

I think there is no regression.


#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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