Messages in this thread | | | Date | Tue, 27 Dec 2011 14:30:12 -0800 | From | Tejun Heo <> | Subject | Re: [PATCHSET] block, mempool, percpu: implement percpu mempool and fix blkcg percpu alloc deadlock |
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Hello, Andrew.
On Tue, Dec 27, 2011 at 02:21:56PM -0800, Andrew Morton wrote: > <autorepeat>For those users who don't want the stats, stats shouldn't > consume any resources at all.
Hmmm.... For common use cases - a few cgroups doing IOs to most likely single physical device and maybe a couple virtual ones, I don't think this would show up anywhere both in terms of memory and process overhead. While avoding it would be nice, I don't think that should be the focus of optimization or design decisions.
> And I bet that the majority of the minority who want stats simply want > to know "how much IO is this cgroup doing", and don't need per-cgroup, > per-device accounting. > > And it could be that the minority of the minority who want per-device, > per-cgroup stats only want those for a minority of the time. > > IOW, what happens if we give 'em atomic_add() and be done with it?
I really don't know. That surely is an enticing idea tho. Jens, Vivek, can you guys chime in? Is gutting out (or drastically simplifying) cgroup-dev stats an option? Are there users who are actually interested in this stuff?
Thanks.
-- tejun
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