On Wed, Apr 10, 2013 at 03:28:32PM -0700, dormando wrote: > > On Tue, Apr 09, 2013 at 05:27:18PM +0000, Christoph Lameter wrote: > > > One additional measure that may be useful is to make kswapd prefer one > > > specific processor on a socket. Two benefits arise from that: > > > > > > 1. Better use of cpu caches and therefore higher speed, less > > > serialization. > > > > > > > Considering the volume of pages that kswapd can scan when it's active > > I would expect that it trashes its cache anyway. The L1 cache would be > > flushed after scanning struct pages for just a few MB of memory. > > > > > 2. Reduction of the disturbances to one processor. > > > > > > > I've never checked it but I would have expected kswapd to stay on the > > same processor for significant periods of time. Have you experienced > > problems where kswapd bounces around on CPUs within a node causing > > workload disruption? > > When kswapd shares the same CPU as our main process it causes a measurable > drop in response time (graphs show tiny spikes at the same time memory is > freed). Would be nice to be able to ensure it runs on a different core > than our latency sensitive processes at least. We can pin processes to > subsets of cores but I don't think there's a way to keep kswapd from > waking up on any of them? I've never tried it myself but does the following work? taskset -p MASK `pidof kswapd` where MASK is a cpumask describing what CPUs kswapd can run on? Obviously care should be taken to ensure that you bind kswapd to a CPU running on the node kswapd cares about. -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>