Messages in this thread | | | Date | Mon, 30 Jan 2012 16:24:13 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: how to make memory.memsw.failcnt is nonzero |
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On Mon, 30 Jan 2012 10:47:33 +0800 Peng Haitao <penght@cn.fujitsu.com> wrote:
> > Michal Hocko said the following on 2012-1-6 18:12: > >> If there is something wrong, I think the bug will be in mem_cgroup_do_charge() > >> of mm/memcontrol.c > >> > >> 2210 ret = res_counter_charge(&memcg->res, csize, &fail_res); > >> 2211 > >> 2212 if (likely(!ret)) { > ... > >> 2221 flags |= MEM_CGROUP_RECLAIM_NOSWAP; > >> 2222 } else > >> 2223 mem_over_limit = mem_cgroup_from_res_counter(fail_res, res); > >> > >> When hit memory.limit_in_bytes, res_counter_charge() will return -ENOMEM, > >> this will execute line 2222: } else. > >> But I think when hit memory.limit_in_bytes, the function should determine further > >> to memory.memsw.limit_in_bytes. > >> This think is OK? > > > > I don't think so. We have an invariant (hard limit is "stronger" than > > memsw limit) memory.limit_in_bytes <= memory.memsw.limit_in_bytes so > > when we hit the hard limit we do not have to consider memsw because > > resource counter: > > a) we already have to do reclaim for hard limit > > b) we check whether we might swap out later on in > > mem_cgroup_hierarchical_reclaim (root_memcg->memsw_is_minimum) so we > > will not end up swapping just to make hard limit ok and go over memsw > > limit. > > > > Please also note that we will retry charging after reclaim if there is a > > chance to meet the limit. > > Makes sense? > > Yeah. > > But I want to test memory.memsw.failcnt is nonzero, how steps? > Thanks. >
Here is a quick hacked test program. see below.
A rough test.
[root@bluextal memcg_test]# cgcreate -g memory:X [root@bluextal memcg_test]# cgset -r memory.limit_in_bytes=200M X [root@bluextal memcg_test]# cgset -r memory.memsw.limit_in_bytes=300M X [root@bluextal memcg_test]# cgexec -g memory:X ./check 200 300 [root@bluextal memcg_test]# echo 0 > /cgroup/memory/X/memory.memsw.failcnt [root@bluextal memcg_test]# cat /cgroup/memory/X/memory.memsw.failcnt 0 [root@bluextal memcg_test]# cgexec -g memory:X ./check 200 300 Killed <-----------------------------------------------------------------------OOM Killed. [root@bluextal memcg_test]# cat /cgroup/memory/X/memory.memsw.failcnt 17 <-----------------------------------------------------------------------memsw failcnt up.
Easy way is 1. allocate memory in Anon. 2. kick out anon memory to swap as much as possible by file I/O.-------(*1) 3. delete file cache by some way (I used unlink() here.) --------------(*2) 4. allocate anon memory.
The important points are (*1) and (*2). see a program below.
You can prevent OOM (freeze-at-oom) by [root@bluextal memcg_test]# cgset -r memory.oom_control=1 X
Here is the memory.stat at OOM.
[root@bluextal test]# cat /cgroup/memory/X/memory.stat cache 0 rss 209666048 mapped_file 0 pgpgin 30567 pgpgout 72381 swap 104906752 <snip> hierarchical_memory_limit 209715200 hierarchical_memsw_limit 314572800
rss+cache < memory.limit rss+swap == memsw.limit.
== #include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #include <sys/mman.h> #include <string.h>
int main(int argc, char *argv[]) { char filename[] = "./tmpfile-for-test"; unsigned long mem_size = atoi(argv[1]); unsigned long memsw_size = atoi(argv[2]); unsigned long file_size; int fd, len; char *addr, *buf;
if (memsw_size < 100) return 0; mem_size *= 1024 * 1024; memsw_size *= 1024 * 1024;
memsw_size = memsw_size - 10 * 1024 * 1024; /* 10M Bytes of margin */ addr = mmap(NULL, memsw_size, PROT_READ|PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
/* allocate pages and cause swap out */ memset(addr, 0, memsw_size);
/* create file, this will make more swaps. */ file_size = mem_size * 80 / 100;
fd = open(filename, O_RDWR| O_TRUNC, 0644);
buf = malloc(1024 *1024);
for (len = 0; len < file_size; len += 1024*1024) { write(fd, buf, 1024*1024); } /* read the file again */ lseek(fd, SEEK_SET, 0); for (len = 0; len < file_size; len += 1024 * 1024) read(fd, buf, 1024 * 1024); lseek(fd, SEEK_SET, 0); for (len = 0; len < file_size; len += 1024 * 1024) read(fd, buf, 1024 * 1024); unlink(filename);
addr = malloc(9 * 1024 * 1024); memset(addr, 0, 9 * 1024 * 1024); printf("done\n"); sleep(100); }
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