On Sat, 24 Sep 2011 11:45:04 -0300 Glauber Costa <glommer@xxxxxxxxxxxxx> wrote: > On 09/22/2011 12:09 PM, Balbir Singh wrote: > > On Thu, Sep 22, 2011 at 11:30 AM, Greg Thelen<gthelen@xxxxxxxxxx> wrote: > >> On Wed, Sep 21, 2011 at 11:59 AM, Glauber Costa<glommer@xxxxxxxxxxxxx> 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 > Do you guys see it as a showstopper for this series to be merged, or can > we just TODO it ? > In my experience, 'I can't rmdir cgroup.' is always an important/difficult problem. The users cannot know where the accouting is leaking other than kmem.usage_in_bytes or memory.usage_in_bytes. and can't fix the issue. please add EXPERIMENTAL to Kconfig until this is fixed. > I can push a proposal for it, but it would be done in a separate patch > anyway. Also, we may be in better conditions to fix this when the slab > part is merged - since it will likely have the same problems... > Yes. considering sockets which can be shared between tasks(cgroups) you'll finally need - owner task of socket - account moving callback Or disallow task moving once accounted. 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>