Messages in this thread | | | Subject | [RFC 0/4]x86: allocate up to 32 tlb invalidate vectors | From | Shaohua Li <> | Date | Wed, 03 Nov 2010 14:44:15 +0800 |
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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.
Thanks, Shaohua
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