Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269037AbUIHDmQ (ORCPT ); Tue, 7 Sep 2004 23:42:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266512AbUIHDky (ORCPT ); Tue, 7 Sep 2004 23:40:54 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:17317 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S269028AbUIHDjW (ORCPT ); Tue, 7 Sep 2004 23:39:22 -0400 Date: Tue, 7 Sep 2004 23:18:16 -0300 From: Marcelo Tosatti To: Con Kolivas Cc: Andrew Morton , raybry@sgi.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, riel@redhat.com, piggin@cyberone.com.au, mbligh@aracnet.com Subject: Re: swapping and the value of /proc/sys/vm/swappiness Message-ID: <20040908021816.GB2942@logos.cnet> References: <413CB661.6030303@sgi.com> <20040906162740.54a5d6c9.akpm@osdl.org> <20040907000304.GA8083@logos.cnet> <20040907212051.GC3492@logos.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040907212051.GC3492@logos.cnet> User-Agent: Mutt/1.5.5.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3549 Lines: 66 > Spent some time doing a few tests. > > A contained test (512MB box, allocate 450MB of memory, touch and sleep + > huge dd) show's that 2.6.6 and 2.6.7 are equivalent (swapout 120-150M when the "dd" > starts writing out data). > > 2.6.9-rc1 swaps out 350M on the same test. Doenst seem nice, I'll try to isolate > what causes this tomorrow (this is probably what is hitting desktop users which > is fixed by Con's patches). Thats problem #1. Something needs a little tweaking > I think. > > Ray, I see the additional swapouts increase the dd performance for your particular testcase: > > on 2.6.6: > Total I/O Avg Swap min max pg cache min max > ----------- --------- ------- ------ --------- ------- ------- > 0 242.47 MB/s 0 MB ( 0, 0) 3195 MB ( 3138, 3266) > 20 256.06 MB/s 0 MB ( 0, 0) 3170 MB ( 3074, 3234) > 40 267.29 MB/s 0 MB ( 0, 0) 3189 MB ( 3137, 3234) > 60 289.43 MB/s 666 MB ( 72, 1680) 3847 MB ( 3296, 4817) <---------- > > So for this one testcase it is being beneficial. > > However, decreasing the "swappiness" value does not seem to make much of a difference: > > Kernel Version 2.6.8.1-mm4: > Total I/O Avg Swap min max pg cache min max > ----------- --------- ------- ------ --------- ------- ------- > 0 287.28 MB/s 710 MB ( 46, 3060) 4082 MB ( 3426, 6308) > 20 288.05 MB/s 508 MB ( 94, 1417) 3848 MB ( 3442, 4739) > 40 287.03 MB/s 588 MB ( 199, 1251) 3909 MB ( 3570, 4515) > 60 290.08 MB/s 640 MB ( 210, 1190) 3976 MB ( 3538, 4531) > 80 287.73 MB/s 693 MB ( 316, 1195) 4049 MB ( 3713, 4545) > 100 166.17 MB/s 26001 MB ( 26001, 26002) 28798 MB ( 28740, 28852) > > Kernel Version 2.6.9-rc1-mm3: > Total I/O Avg Swap min max pg cache min max > ----------- --------- ------- ------ --------- ------- ------- > 0 274.80 MB/s 10511 MB ( 5644, 14492) 13293 MB ( 8596, 17156) > 20 267.02 MB/s 12624 MB ( 5578, 16287) 15298 MB ( 8468, 18889) > 40 267.66 MB/s 13541 MB ( 6619, 17461) 16199 MB ( 9393, 20044) > 60 233.73 MB/s 18094 MB ( 16550, 19676) 20629 MB ( 19103, 22192) > 80 213.64 MB/s 20950 MB ( 15844, 22977) 23450 MB ( 18496, 25440) > 100 164.58 MB/s 26004 MB ( 26004, 26004) 28410 MB ( 28327, 28455) > > And that is a problem #2 - swappinness not being honoured. Guys, > any ideas on the reason for that? Hum I just tested it on my 512MB box and swappiness is working fine on 2.6.8.. (it has expected effects), unlike Ray's tests. > > Andrew, dirty_ratio and dirty_background_ratio (as low as 5% each) did not significantly > affect the amount of swapped out data, only a small effect on _how soon_ anonymous > memory was swapped out. > > And finally, Ray, the difference you see between 2.6.6 and 2.6.7 can be explained, > as noted by others in this thread, to vmscan.c changes (page replacement/scanning policy > changes were made). > > Will continue with more tests tomorrow. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/