On Mon, Jun 03, 2013 at 11:20:32AM -0400, Johannes Weiner wrote: > On Mon, Jun 03, 2013 at 10:25:33AM +0200, Peter Zijlstra wrote: > > On Thu, May 30, 2013 at 02:04:06PM -0400, Johannes Weiner wrote: > > > Previously, page cache radix tree nodes were freed after reclaim > > > emptied out their page pointers. But now reclaim stores shadow > > > entries in their place, which are only reclaimed when the inodes > > > themselves are reclaimed. This is problematic for bigger files that > > > are still in use after they have a significant amount of their cache > > > reclaimed, without any of those pages actually refaulting. The shadow > > > entries will just sit there and waste memory. In the worst case, the > > > shadow entries will accumulate until the machine runs out of memory. > > > > > > > Can't we simply prune all refault entries that have a distance larger > > than the memory size? Then we must assume that no refault entry means > > its too old, which I think is a fair assumption. > > Two workloads bound to two nodes might not push pages through the LRUs > at the same pace, so a distance might be bigger than memory due to the > faster moving node, yet still be a hit in the slower moving one. We > can't really know until we evaluate it on a per-zone basis. But wasn't patch 1 of this series about making sure each zone is scanned proportionally to its size? But given that, sure maybe 1 memory size is a bit strict, but surely we can put a limit on things at about 2 memory sizes? -- 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>