In v3.3-rc1, the global LRU has been removed with commit "mm: make per-memcg LRU lists exclusive". The patch fixes up the memcg docs. Signed-off-by: Ying Han <yinghan@xxxxxxxxxx> --- Documentation/cgroups/memory.txt | 25 ++++++++++++------------- 1 files changed, 12 insertions(+), 13 deletions(-) diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt index 4c95c00..847a2a4 100644 --- a/Documentation/cgroups/memory.txt +++ b/Documentation/cgroups/memory.txt @@ -34,8 +34,7 @@ Current Status: linux-2.6.34-mmotm(development version of 2010/April) Features: - accounting anonymous pages, file caches, swap caches usage and limiting them. - - private LRU and reclaim routine. (system's global LRU and private LRU - work independently from each other) + - pages are linked to per-memcg LRU exclusively, and there is no global LRU. - optionally, memory+swap usage can be accounted and limited. - hierarchical accounting - soft limit @@ -154,7 +153,7 @@ updated. page_cgroup has its own LRU on cgroup. 2.2.1 Accounting details All mapped anon pages (RSS) and cache pages (Page Cache) are accounted. -Some pages which are never reclaimable and will not be on the global LRU +Some pages which are never reclaimable and will not be on the LRU are not accounted. We just account pages under usual VM management. RSS pages are accounted at page_fault unless they've already been accounted @@ -209,19 +208,19 @@ In this case, setting memsw.limit_in_bytes=3G will prevent bad use of swap. By using memsw limit, you can avoid system OOM which can be caused by swap shortage. -* why 'memory+swap' rather than swap. -The global LRU(kswapd) can swap out arbitrary pages. Swap-out means -to move account from memory to swap...there is no change in usage of -memory+swap. In other words, when we want to limit the usage of swap without -affecting global LRU, memory+swap limit is better than just limiting swap from -OS point of view. - * What happens when a cgroup hits memory.memsw.limit_in_bytes When a cgroup hits memory.memsw.limit_in_bytes, it's useless to do swap-out in this cgroup. Then, swap-out will not be done by cgroup routine and file -caches are dropped. But as mentioned above, global LRU can do swapout memory -from it for sanity of the system's memory management state. You can't forbid -it by cgroup. +caches are dropped. + +TODO: +* use 'memory+swap' rather than swap was due to existence of global LRU. It can +swap out arbitrary pages. Swap-out means to move account from memory to swap... +there is no change in usage of memory+swap. In other words, when we want to +limit the usage of swap without affecting global LRU, memory+swap limit is +better than just limiting swap from OS point of view. However, the global LRU +has been removed now and all pages are linked in private LRU. We might want to +revisit this in the future. 2.5 Reclaim -- 1.7.7.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>