Messages in this thread | | | Date | Thu, 13 Oct 2011 10:54:30 -0500 (CDT) | From | Christoph Lameter <> | Subject | Re: [PATCH] Reduce vm_stat cacheline contention in __vm_enough_memory |
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On Thu, 13 Oct 2011, Dimitri Sivanich wrote:
> > increase the allowed delta per zone if frequent updates occur via the > > overflow checks in vmstat.c. See calculate_*_threshold there. > > I tried changing the threshold in both directions, with slower throughput in > both cases.
If that is the case check for the vm_stat cacheline being shared with another hot kernel variable variable. Maybe that causes cacheline eviction.
If there are no updates occurring for a while (due to increased deltas and/or vmstat updates) then the vm_stat cacheline should be able to stay in shared mode in multiple processors and the performance should increase.
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