Messages in this thread | | | Date | Mon, 15 Nov 2010 09:53:55 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [RFC 0/4]x86: allocate up to 32 tlb invalidate vectors |
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On 11/15/2010 06:02 AM, Shaohua Li wrote: > On Wed, 2010-11-03 at 14:44 +0800, Shaohua Li wrote: >> Hi, >> In workload with heavy page reclaim, flush_tlb_page() is frequently >> used. We currently have 8 vectors for tlb flush, which is fine for small >> machines. But for big machines with a lot of CPUs, the 8 vectors are >> shared by all CPUs and we need lock to protect them. This will cause a >> lot of lock contentions. please see the patch 3 for detailed number of >> the lock contention. >> Andi Kleen suggests we can use 32 vectors for tlb flush, which should be >> fine for even 8 socket machines. Test shows this reduces lock contention >> dramatically (see patch 3 for number). >> One might argue if this will waste too many vectors and leave less >> vectors for devices. This could be a problem. But even we use 32 >> vectors, we still leave 78 vectors for devices. And we now have per-cpu >> vector, vector isn't scarce any more, but I'm open if anybody has >> objections. >> > Hi Ingo & hpa, any comments about this series? >
Hi Shaohua,
It looks good... I need to do a more thorough review and put it in; I just have been consumed a bit too much by a certain internal project.
-hpa
-- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
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