On Mon, May 13, 2013 at 09:12:31AM +0100, Mel Gorman wrote: > This series does not fix all the current known problems with reclaim but > it addresses one important swapping bug when there is background IO. .... > > 3.10.0-rc1 3.10.0-rc1 > vanilla lessdisrupt-v4 > Page Ins 1234608 101892 > Page Outs 12446272 11810468 > Swap Ins 283406 0 > Swap Outs 698469 27882 > Direct pages scanned 0 136480 > Kswapd pages scanned 6266537 5369364 > Kswapd pages reclaimed 1088989 930832 > Direct pages reclaimed 0 120901 > Kswapd efficiency 17% 17% > Kswapd velocity 5398.371 4635.115 > Direct efficiency 100% 88% > Direct velocity 0.000 117.817 > Percentage direct scans 0% 2% > Page writes by reclaim 1655843 4009929 > Page writes file 957374 3982047 Lots more file pages are written by reclaim. Is this from kswapd or direct reclaim? If it's direct reclaim, what happens when you run on a filesystem that doesn't allow writeback from direct reclaim? Also, what does this do to IO patterns and allocation? This tends to indicate that the background flusher thread is not doing the writeback work fast enough when memory is low - can you comment on this at all, Mel? Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- 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>