Messages in this thread | | | Date | Mon, 10 Aug 2009 15:22:05 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: Help Resource Counters Scale Better (v3) |
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On Mon, 10 Aug 2009 14:45:59 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > Do you agree? > > Ok. Config is enough at this stage. > > The last advice for merge is, it's better to show the numbers or > ask someone who have many cpus to measure benefits. Then, Andrew can > know how this is benefical. > (My box has 8 cpus. But maybe your IBM collaegue has some bigger one) > > In my experience (in my own old trial), > - lock contention itself is low. not high. > - but cacheline-miss, pingpong is very very frequent. > > Then, this patch has some benefit logically but, in general, > File-I/O, swapin-swapout, page-allocation/initalize etc..dominates > the performance of usual apps. You'll have to be careful to select apps > to measure the benfits of this patch by application performance. > (And this is why I don't feel so much emergency as you do) >
Why I say "I want to see the numbers" again and again is that this is performance improvement with _bad side effect_. If this is an emergent trouble, and need fast-track, which requires us "fix small problems later", plz say so.
I have no objection to this approach itself because I can't think of something better, now. percpu-counter's error tolerance is a generic problem and we'll have to visit this anyway.
Thanks, -Kame
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