Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx> writes: > On Wed, 18 Aug 2010, Chris Webb wrote: > > > > != 0. And even then, zone reclaim should only reclaim file pages, not > > > anon. In theory... > > > > Hi. This is zero on all our machines: > > > > # sysctl vm.zone_reclaim_mode > > vm.zone_reclaim_mode = 0 > > Set it to 1. I tried this on a handful of the problem hosts before re-adding their swap. One of them now runs without dipping into swap. The other three I tried had the same behaviour of sitting at zero swap usage for a while, before suddenly spiralling up with %wait going through the roof. I had to swapoff on them to bring them back into a sane state. So it looks like it helps a bit, but doesn't cure the problem. I could definitely believe an explanation that we're swapping in preference to allocating remote zone pages somehow, given the imbalance in free memory between the nodes which we saw. However, I read the documentation for vm.zone_reclaim_mode, which suggests to me that when it was set to zero, pages from remote zones should be allocated automatically in preference to swap given that zone_reclaim_mode & 4 == 0? Cheers, Chris. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>