From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 1 Aug 2001 07:52:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 1 Aug 2001 07:52:30 -0400 Received: from picard.csihq.com ([204.17.222.1]:24493 "EHLO picard.csihq.com") by vger.kernel.org with ESMTP id ; Wed, 1 Aug 2001 07:52:17 -0400 Message-ID: <020001c11a80$43297110$e1de11cc@csihq.com> From: "Mike Black" To: , Cc: , , "Andrew Morton" In-Reply-To: <20010801105419.8F078424A@lists.samba.org> Subject: Re: 2.4.8preX VM problems Date: Wed, 1 Aug 2001 07:51:09 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This sounds a lot like the problem I've been having with ext3 and raid. A one-thread tiobench performs just great. A two-thread tiobench starts having lots of kswapd action when free memory gets down to ~5Meg. ext3 exacerbates the problem. kswapd kicks up it's heals and starts grinding away (and NEVER swaps anything out). I've been working this with Andrew Morton (the ext3 guy). I have come to the opinion that kswapd needs to be a little smarter -- if it doesn't find anything to swap shouldn't it go to sleep a little longer before trying again? That way it could gracefully degrade itself when it's not making any progress. In my testing (on a dual 1Ghz/2G machine) the machine "locks up" for long periods of time while kswapd runs around trying to do it's thing. If I could disable kswapd I would just to test this. I tried to figure out how to lengthen the sleep time of kswapd but didn't have time to chase it down (it wasn't intuitively obvious :-) ________________________________________ Michael D. Black Principal Engineer mblack@csihq.com 321-676-2923,x203 http://www.csihq.com Computer Science Innovations http://www.csihq.com/~mike My home page FAX 321-676-2355 ----- Original Message ----- From: "Andrew Tridgell" To: Cc: ; Sent: Wednesday, August 01, 2001 6:54 AM Subject: Re: 2.4.8preX VM problems Marcelo, > The following patch sets the zone free target to freepages.high. Can you > test it ? (I tried here and got the expected results) Running just that patch against 2.4.8pre3 gives: [root@fraud /root]# ~/readfiles /dev/ddisk 198 MB 198.084 MB/sec 386 MB 188.634 MB/sec 570 MB 183.827 MB/sec 743 MB 172.5 MB/sec 810 MB 67.0501 MB/sec 862 MB 52.1381 MB/sec 901 MB 37.9501 MB/sec 957 MB 55.8253 MB/sec 998 MB 41.1541 MB/sec 1046 MB 48.1661 MB/sec 1088 MB 40.3898 MB/sec 1140 MB 50.8782 MB/sec 1183 MB 42.5749 MB/sec 1229 MB 46.1378 MB/sec 1275 MB 44.8515 MB/sec 1319 MB 43.5389 MB/sec 1368 MB 47.5747 MB/sec 1411 MB 42.8134 MB/sec which is much better, but is pretty poor performance for a null device. Running with that latest patch plus the patch you sent previously gives roughly the same result. Also, kswapd chews lots of cpu during these runs: CPU0 states: 0.0% user, 79.0% system, 0.0% nice, 20.4% idle CPU1 states: 0.2% user, 77.1% system, 0.0% nice, 22.1% idle Mem: 2059088K av, 892256K used, 1166832K free, 0K shrd, 784972K buff Swap: 1052216K av, 0K used, 1052216K free 10072K cached PID USER PRI NI SIZE RSS SHARE LC STAT %CPU %MEM TIME COMMAND 608 root 19 0 452 452 328 1 R 95.2 0.0 1:23 readfiles 5 root 14 0 0 0 0 1 SW 58.3 0.0 0:52 kswapd 6 root 9 0 0 0 0 1 RW 2.1 0.0 0:01 kreclaimd - 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/