From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 15 Oct 2008 23:31:26 -0700 From: Andrew Morton Subject: Re: mm-more-likely-reclaim-madv_sequential-mappings.patch Message-Id: <20081015233126.27885bb9.akpm@linux-foundation.org> In-Reply-To: <20081016151030.5832.KOSAKI.MOTOHIRO@jp.fujitsu.com> References: <20081016143830.582C.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20081015230659.a717d0b6.akpm@linux-foundation.org> <20081016151030.5832.KOSAKI.MOTOHIRO@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: KOSAKI Motohiro Cc: linux-mm@kvack.org, Johannes Weiner List-ID: On Thu, 16 Oct 2008 15:22:15 +0900 (JST) KOSAKI Motohiro wrote: > > > 2.6.27 mmotm-1010 > > > ============================================================== > > > mm_sync_madv_cp 6:14 6:02 (min:sec) > > > dbench throughput 12.1507 14.6273 (MB/s) > > > dbench latency 33046 21779 (ms) > > > > > > > > > So, throughput improvement is relativily a bit, but latency improvement is much. > > > Then, I think the patch can improve "larege file copy (e.g. backup operation) > > > attacks desktop latency" problem. > > > > > > Any comments? > > > > > > > Sounds good. > > > > But how do we know that it was this particular patch which improved the > > latency performance? > > In my concern, > > dbench's pages are touched multiple times, but copy's pages are touched only twice. > Then, on 2.6.27, copy's page transit to inactive -> active -> inactive -> free. > it decrease latency meaninglessly. > > IOW, 2.6.27 model > > 1. shrink_inactive_lsit() promote copy's page to active (it touched twice (readahead + memcpy)) > 2. shrink_active_list() demote dbench's page > 3. shrink_inactive_list() promote dbench's page (because it is touched multiple times) > 4. shrink_active_list() demote copy's page > 5. shrink_inactive_list() free copy's page > > > mmotm mode, > > 1, shrink_inactive_list() free copy's page. > 2. end! OK. But my concern is that perhaps the above latency improvement was caused by one of the many other MM patches in mmotm. Reverting mm-more-likely-reclaim-madv_sequential-mappings.patch from mmotm and rerunning the tests would be the way to determine this. (hint :) - thanks). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org