On Sun, Aug 01, 2010 at 07:56:40PM +0800, Wu Fengguang wrote: > > Sigh. We have sooo many problems with writeback and latency. Read > > https://bugzilla.kernel.org/show_bug.cgi?id=12309 and weep. Everyone's > > running away from the issue and here we are adding code to solve some > > alleged stack-overflow problem which seems to be largely a non-problem, > > by making changes which may worsen our real problems. > > I'm sweeping bug 12309. Most people reports some data writes, though > relative few explicitly stated memory pressure is another necessary > condition. #14: Per von Zweigbergk Ubuntu 2.6.27 slowdown when copying 25MB/s USB stick to 10 MB/s SSD. KOSAKI and my patches won't fix 2.6.27, since it only do congestion_wait() and wait_on_page_writeback() for order>3 allocations. There may be more bugs there. #24: Per von Zweigbergk The encryption of the SSD very significantly increases the problem. This is expected. Data encryption roughly doubles page consumption speed (there may be temp buffers allocated/dropped quickly), hence vmscan pressure. #26: Per von Zweigbergk Disabling swap makes the terminal launch much faster while copying; However Firefox and vim hang much more aggressively and frequently during copying. It's interesting to see processes behave differently. Is this reproducible at all? #34: Ben Gamari There is evidence that x86-64 is a factor here. Because x86-64 does order-1 page allocation in fork() and consumes more memory (larger user space code/data)? #36: Lari Temmes Go from usable to totally unusable when switching from a SMP kernel to a UP kernel on a single CPU laptop He should be testing 2.6.28. I'm not aware of known bugs there. #47: xyke Renicing pdflush -10 had some great improvement on basic responsiveness. It sure helps :) Too much (old) messages there. I'm hoping some of the still active bug reporters to test the following patches (they are for the -mmotm tree, need to unindent code for Linus's tree) and see if there are any improvements. http://lkml.org/lkml/2010/8/1/40 http://lkml.org/lkml/2010/8/1/45 Thanks, Fengguang -- 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>