On Tue, 02 Oct 2007 19:04:15 +0530
Balbir Singh <[EMAIL PROTECTED]> wrote:
> KAMEZAWA Hiroyuki wrote:
> > Current implementation of memory cgroup controller does following in
> > migration.
> >
> > 1. uncharge when unmapped.
> > 2. charge again when remapped.
> >
> > Consider migrate a page from OLD to NEW.
> >
> > In following case, memory (for page_cgroup) will leak.
> >
> > 1. charge OLD page as page-cache. (charge = 1
> > 2. A process mmap OLD page. (chage + 1 = 2)
> > 3. A process migrates it.
> > try_to_unmap(OLD) (charge - 1 = 1)
> > replace OLD with NEW
> > remove_migration_pte(NEW) (New is newly charged.)
> > discard OLD page. (page_cgroup for OLD page is not reclaimed.)
> >
>
> Interesting test scenario, I'll try and reproduce the problem here.
> Why does discard OLD page not reclaim page_cgroup?
Just because OLD page is not page-cache at discarding. (it is replaced with NEW
page)
>
> > [EMAIL PROTECTED] kamezawa]# ./migrate_test 512Mfile 1 &
> > [1] 4108
> > #At the end of migration,
>
> Where can I find migrate_test?
>
here, (just I wrote for this test. works on my RHEL5/2.6.18-rc8-mm2/ia64 NUMA
box)
This program doesn't check 'where is file cache ?' before migration. So please
check it by yourself before run.
==
#include <stdio.h>
#include <stdlib.h>
#include <syscall.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <numaif.h>
#include <unistd.h>
#define PAGESIZE (16384)
static inline int move_pages(pid_t pid, unsigned long nr_pages,
const void **address,
const int *nodes, int *status, int flags)
{
return syscall(SYS_move_pages, pid, nr_pages, address,
nodes, status, flags);
}
/*
* migrate_test.c -- mmap file and migrate it to specified node.
* %migrate_task file nodeid
*
*/
int main(int argc, char *argv[])
{
int ret, fd, val, node[1], status[1];
char *addr, *c;
unsigned long size, nr_pages, pos;
struct stat statbuf;
void *address[1];
int target;
if (argc != 3) {
fprintf(stderr,"usage: migrate_test file node\n");
exit(0);
}
target = atoi(argv[2]);
fd = open(argv[1], O_RDONLY);
if (fd < 0) {
perror("open");
exit(1);
}
ret = fstat(fd, &statbuf);
if (ret < 0) {
perror("fstat");
exit(1);
}
size = statbuf.st_size;
nr_pages = size/PAGESIZE;
size = nr_pages * PAGESIZE;
addr = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
if (addr == MAP_FAILED) {
perror("mmap");
exit(1);
}
/* Touch all */
for (pos = 0; pos < nr_pages; pos++) {
c = addr + pos * PAGESIZE;
val += *c;
}
/* Move Pages */
for (pos = 0; pos < nr_pages; pos++) {
node[0] = target;
status[0] = 0;
address[0] = addr + pos * PAGESIZE;
ret = move_pages(0, 1, address, node, status,
MPOL_MF_MOVE_ALL);
if (ret) {
perror("move_pages");
}
#if 1
printf("pos %d %p %d %d\n",pos, address[0], node[0], status[0]);
#endif
}
/* Touch all again....maybe unnecessary.*/
for (pos = 0; pos < nr_pages; pos++) {
c = addr + pos * PAGESIZE;
val += *c;
}
while (1) {
/* mmap until killed */
pause();
}
printf("val %d\n",val);
return 0;
}
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