Messages in this thread | | | Date | Sat, 24 Sep 2011 10:40:53 -0300 | From | Glauber Costa <> | Subject | Re: [PATCH v3 2/7] socket: initial cgroup code. |
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On 09/22/2011 12:09 PM, Balbir Singh wrote: > On Thu, Sep 22, 2011 at 11:30 AM, Greg Thelen<gthelen@google.com> wrote: >> On Wed, Sep 21, 2011 at 11:59 AM, Glauber Costa<glommer@parallels.com> wrote: >>> Right now I am working under the assumption that tasks are long lived inside >>> the cgroup. Migration potentially introduces some nasty locking problems in >>> the mem_schedule path. >>> >>> Also, unless I am missing something, the memcg already has the policy of >>> not carrying charges around, probably because of this very same complexity. >>> >>> True that at least it won't EBUSY you... But I think this is at least a way >>> to guarantee that the cgroup under our nose won't disappear in the middle of >>> our allocations. >> >> Here's the memcg user page behavior using the same pattern: >> >> 1. user page P is allocate by task T in memcg M1 >> 2. T is moved to memcg M2. The P charge is left behind still charged >> to M1 if memory.move_charge_at_immigrate=0; or the charge is moved to >> M2 if memory.move_charge_at_immigrate=1. >> 3. rmdir M1 will try to reclaim P (if P was left in M1). If unable to >> reclaim, then P is recharged to parent(M1). >> > > We also have some magic in page_referenced() to remove pages > referenced from different containers. What we do is try not to > penalize a cgroup if another cgroup is referencing this page and the > page under consideration is being reclaimed from the cgroup that > touched it. > > Balbir Singh Btw:
This has the same problem we'll face for any kmem related memory in the cgroup: We can't just force reclaim to make the cgroup empty...
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