On Sat, Mar 09, 2013 at 10:00:37AM +0800, Will Huck wrote: > Hi Johannes, > On 03/08/2013 10:35 AM, Johannes Weiner wrote: > >On Thu, Mar 07, 2013 at 06:07:23PM -0800, Raymond Jennings wrote: > >>Just a two cent question, but is there any merit to having the kernel > >>defragment swap space? > >That is a good question. > > > >Swap does fragment quite a bit, and there are several reasons for > >that. > > Are there any tools to test and monitor swap subsystem and page > reclaim subsystem? seekwatcher is great to see the IO patterns. Anything that uses anonymous memory can test swap: a java job, multiplying matrixes, kernel builds etc. I mostly log /proc/vmstat by taking snapshots at a regular interval during the workload, then plot and visually correlate the swapin/swapout counters with the individual LRU sizes, page fault rate, what have you, to get a feeling for what it's doing. -- 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>