Messages in this thread | | | Subject | Re: [PATCH 0/4]x86: allocate up to 32 tlb invalidate vectors -resend | From | Shaohua Li <> | Date | Mon, 14 Feb 2011 10:38:18 +0800 |
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On Mon, 2011-01-17 at 10:51 +0800, Shaohua Li wrote: > last post is lost, resent. > > 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. any comments on this patch set?
Thanks, Shaohua
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