On 02/24/2013 02:38 PM, Phillip Susi wrote: > On 02/24/2013 04:25 PM, Dave Hansen wrote: >> Essentially, they don't want any I/O initiated except that which >> is initiated by the app. If you let the system get in to reclaim, >> it'll start doing dirty writeout for pages other than those the app >> is interested in. > > Are you talking about IO initiated by the app, or other tasks in the > system? If the former then it won't be affected by this change. Once we go in to reclaim, we'll start writeback on dirty pages. The VM's writeback patterns are not as efficient as if the app itself was initiating them from sync_file_range(), and we see massive throughput loss on the disk. >From the looks of your patch, deactivating all the pages (if clean of course) will get them on the LRU, and should keep any direct-reclaiming tasks from actually going and initiating any additional I/O. It looks like a promising approach, at least theoretically. I'll definitely test and see if it works in practice. -- 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>