diff options
| author | KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> | 2009-01-07 18:07:56 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-01-08 08:31:05 -0800 |
| commit | d13d144309d2e5a3e6ad978b16c1d0226ddc9231 (patch) | |
| tree | 37c19902b527823956db969d9428737081b2a94d /Documentation | |
| parent | c1e862c1f5ad34771b6d0a528cf681e0dcad7c86 (diff) | |
memcg: handle swap caches
SwapCache support for memory resource controller (memcg)
Before mem+swap controller, memcg itself should handle SwapCache in proper
way. This is cut-out from it.
In current memcg, SwapCache is just leaked and the user can create tons of
SwapCache. This is a leak of account and should be handled.
SwapCache accounting is done as following.
charge (anon)
- charged when it's mapped.
(because of readahead, charge at add_to_swap_cache() is not sane)
uncharge (anon)
- uncharged when it's dropped from swapcache and fully unmapped.
means it's not uncharged at unmap.
Note: delete from swap cache at swap-in is done after rmap information
is established.
charge (shmem)
- charged at swap-in. this prevents charge at add_to_page_cache().
uncharge (shmem)
- uncharged when it's dropped from swapcache and not on shmem's
radix-tree.
at migration, check against 'old page' is modified to handle shmem.
Comparing to the old version discussed (and caused troubles), we have
advantages of
- PCG_USED bit.
- simple migrating handling.
So, situation is much easier than several months ago, maybe.
[hugh@veritas.com: memcg: handle swap caches build fix]
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Tested-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/controllers/memory.txt | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/Documentation/controllers/memory.txt b/Documentation/controllers/memory.txt index 54253b7a8db2..9fe2d0eabe05 100644 --- a/Documentation/controllers/memory.txt +++ b/Documentation/controllers/memory.txt @@ -137,6 +137,11 @@ behind this approach is that a cgroup that aggressively uses a shared page will eventually get charged for it (once it is uncharged from the cgroup that brought it in -- this will happen on memory pressure). +Exception: When you do swapoff and make swapped-out pages of shmem(tmpfs) to +be backed into memory in force, charges for pages are accounted against the +caller of swapoff rather than the users of shmem. + + 2.4 Reclaim Each cgroup maintains a per cgroup LRU that consists of an active |