Messages in this thread | | | Date | Wed, 27 Feb 2008 14:07:16 +0100 | From | Nick Piggin <> | Subject | Re: [rfc][patch] x86-64 new smp_call_function design |
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On Wed, Feb 27, 2008 at 02:04:18PM +0100, Andi Kleen wrote: > > > On a 2 socket, 8 core system, I see anywhere up to nearly 16x better > > performance on a stress test. The common cases of call-all, and wait > > are improved the least, however I think that if call-single and nowait > > are turned into a high performance API, then new usages will pop up > > (eg. I started this because I wanted to do "call single, nowait" calls > > for migrating block IO completions back to submitting CPU; however I > > am also interested in improving the "call all, wait" case for example > > to improve vmalloc tlb flushing). > > TLB flushing at least on x86-64 should be already well optimized on its > own. I would be surprised if you could do much better.
*vmalloc* TLB flushing.
void flush_tlb_all(void) { on_each_cpu(do_flush_tlb_all, NULL, 1, 1); }
Of course we could use a new vector for it and speed it up a lot more, but after my vmalloc improvements I think that would be a waste of a vector at this point.
> > As far as I understand, calling a subset of online CPUs that is not all or > > one, is used quite infrequently, so this might be OK. > > With cpusets and isolation etc. it is the normal case.
Oh really? Coming from what callers?
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