On Fri, 3 Feb 2012 12:15:59 -0800 Ying Han <yinghan@xxxxxxxxxx> wrote: > On Fri, Feb 3, 2012 at 8:11 AM, Michal Hocko <mhocko@xxxxxxx> wrote: > > On Thu 02-02-12 17:37:13, Ying Han wrote: > >> 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> > > > > For the global LRU removal > > Acked-by: Michal Hocko <mhocko@xxxxxxx> > > > > see the comment about the swap extension bellow. > > > > Thanks > > > >> --- > >> 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 > > [...] > >> @@ -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. > > I wasn't sure about the initial comment while making the patch. Since > it mentions something about global LRU, which i figured we need to > revisit it anyway. > The "global LRU" here means 'the health of the whole memory management". memory+swap guarantees memcg will never be obstacles for routines which works for system memory management. soft-limit _is_ a hint for global lru. but memory+swap will never be. Thanks, -Kame -- 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>