Hi, On Mon 28-03-11 11:01:18, Ying Han wrote: > On Mon, Mar 28, 2011 at 2:39 AM, Michal Hocko <mhocko@xxxxxxx> wrote: > > Hi all, > > > > Memory cgroups can be currently used to throttle memory usage of a group of > > processes. It, however, cannot be used for an isolation of processes from > > the rest of the system because all the pages that belong to the group are > > also placed on the global LRU lists and so they are eligible for the global > > memory reclaim. > > > > This patchset aims at providing an opt-in memory cgroup isolation. This > > means that a cgroup can be configured to be isolated from the rest of the > > system by means of cgroup virtual filesystem (/dev/memctl/group/memory.isolated). > > Thank you Hugh pointing me to the thread. We are working on similar > problem in memcg currently > > Here is the problem we see: > 1. In memcg, a page is both on per-memcg-per-zone lru and global-lru. > 2. Global memory reclaim will throw page away regardless of cgroup. > 3. The zone->lru_lock is shared between per-memcg-per-zone lru and global-lru. This is the primary motivation for the patchset. Except that I do not insist on the strict isolation because I found opt-in approach less invasive because you have to know what you are doing while you are setting up a group. If the thing is enabled by default we can see many side-effects during the reclaim, I am afraid. > And we know: > 1. We shouldn't do global reclaim since it breaks memory isolation. > 2. There is no need for a page to be on both LRU list, especially > after having per-memcg background reclaim. > > So our approach is to take off page from global lru after it is > charged to a memcg. Only pages allocated at root cgroup remains in > global LRU, and each memcg reclaims pages on its isolated LRU. This sounds like an instance where all cgroups are isolated by default (this can be set by mem_cgroup->isolated = 1). Thanks -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx 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>