On Mon, Oct 29, 2007 at 01:57:40AM +0530, Balbir Singh wrote:
Hugh Dickins wrote:
[snip]
> Without your mem_cgroup mods in mm/swap_state.c, unuse_pte makes
> the right assignments (I believe). But I find that swapout (using
> 600M in a 512M machine) from a 200M cgroup quickly OOMs, whereas
> it behaves correctly with your mm/swap_state.c.
>
On my UML setup, I booted the UML instance with 512M of memory and
used the swapout program that you shared. I tried two things
1. Ran swapout without any changes. The program ran well without
any OOM condition occuring, lot of reclaim occured.
2. Ran swapout with the changes to mm/swap_state.c removed (diff below)
and I still did not see any OOM. The reclaim count was much lesser
since swap cache did not get accounted back to the cgroup from
which pages were being evicted.
I am not sure why I don't see the OOM that you see, still trying. May be
I missing something obvious at this late hour in the night :-)
Output of the tests
-------------------
[EMAIL PROTECTED]:/container/swapout$ cat memory.limit_in_bytes
209715200
[EMAIL PROTECTED]:/container/swapout$ cat memory.usage_in_bytes
65536
[EMAIL PROTECTED]:/container/swapout$ cat tasks
1815
1847
[EMAIL PROTECTED]:/container/swapout$ ps
PID TTY TIME CMD
1815 pts/0 00:00:00 bash
1848 pts/0 00:00:00 ps
[EMAIL PROTECTED]:/container/swapout$ ~/swapout
[EMAIL PROTECTED]:/container/swapout$ echo $?
0
[EMAIL PROTECTED]:/container/swapout$ cat memory.failcnt
18
Diff to remove mods from swap_state.c (for testing only)
--------------------------------------------------------
--- mm/swap_state.c.org 2007-10-29 01:42:14.000000000 +0530
+++ mm/swap_state.c 2007-10-29 01:52:48.000000000 +0530
@@ -79,10 +79,6 @@ static int __add_to_swap_cache(struct pa
BUG_ON(PageSwapCache(page));
BUG_ON(PagePrivate(page));
- error = mem_cgroup_cache_charge(page, current->mm, gfp_mask);
- if (error)
- goto out;
-
error = radix_tree_preload(gfp_mask);
if (!error) {
write_lock_irq(&swapper_space.tree_lock);
@@ -94,14 +90,11 @@ static int __add_to_swap_cache(struct pa
set_page_private(page, entry.val);
total_swapcache_pages++;
__inc_zone_page_state(page, NR_FILE_PAGES);
- } else
- mem_cgroup_uncharge_page(page);
+ }
write_unlock_irq(&swapper_space.tree_lock);
radix_tree_preload_end();
- } else
- mem_cgroup_uncharge_page(page);
-out:
+ }
return error;
}
@@ -141,7 +134,6 @@ void __delete_from_swap_cache(struct pag
BUG_ON(PageWriteback(page));
BUG_ON(PagePrivate(page));
- mem_cgroup_uncharge_page(page);
radix_tree_delete(&swapper_space.page_tree, page_private(page));
set_page_private(page, 0);
ClearPageSwapCache(page);
--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL
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