On Tue, 15 Dec 2009 12:46:32 +0200 "Kirill A. Shutemov" <[email protected]> wrote:
> On Tue, Dec 15, 2009 at 3:58 AM, KAMEZAWA Hiroyuki > <[email protected]> wrote: > > On Sat, 12 Dec 2009 00:59:19 +0200 > > "Kirill A. Shutemov" <[email protected]> wrote: > > If you use have to use spinlock here, this is a system-wide spinlock, > > threshold as "100" is too small, I think. > > What is reasonable value for THRESHOLDS_EVENTS_THRESH for you? > > In most cases spinlock taken only for two checks. Is it significant time? > I tend to think about "bad case" when I see spinlock. And...I'm not sure but, recently, there are many VM users. spinlock can be a big pitfall in some enviroment if not para-virtualized. (I'm sorry I misunderstand somehing and VM handle this well...) > Unfortunately, I can't test it on a big box. I have only dual-core system. > It's not enough to test scalability. > please leave it as 100 for now. But there is a chance to do simple optimization for reducing the number of checks. example) static void mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap) { /* For handle memory allocation in rush, check jiffies */ */ smp_rmb(); if (memcg->last_checkpoint_jiffies == jiffies) return; /* reset event to half value ..*/ memcg->last_checkpoint_jiffies = jiffies; smp_wmb(); ..... I think this kind of check is necessary for handle "Rushing" memory allocation in scalable way. Above one is just an example, 1 tick may be too long. Other simple plan is /* Allow only one thread to do scan the list at the same time. */ if (atomic_inc_not_zero(&memcg->threahold_scan_count) { atomic_dec(&memcg->threshold_scan_count); return; } ... atomic_dec(&memcg->threahold_scan_count) Some easy logic (as above) for taking care of scalability and commenary for that is enough at 1st stage. Then, if there seems to be a trouble/concern, someone (me?) will do some work later. Thanks, -Kame _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
