From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262157AbULCL37 (ORCPT ); Fri, 3 Dec 2004 06:29:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262159AbULCL37 (ORCPT ); Fri, 3 Dec 2004 06:29:59 -0500 Received: from ns.virtualhost.dk ([195.184.98.160]:3992 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S262157AbULCL3y (ORCPT ); Fri, 3 Dec 2004 06:29:54 -0500 Date: Fri, 3 Dec 2004 12:29:14 +0100 From: Jens Axboe To: "Prakash K. Cheemplavam" Cc: Andrew Morton , Linux Kernel , nickpiggin@yahoo.com.au Subject: Re: Time sliced CFQ io scheduler Message-ID: <20041203112914.GM10492@suse.de> References: <20041203070108.GA10492@suse.de> <41B02DFD.9090503@gmx.de> <20041203012645.21377669.akpm@osdl.org> <20041203093903.GE10492@suse.de> <41B03722.5090001@gmx.de> <20041203103130.GH10492@suse.de> <20041203103828.GI10492@suse.de> <41B043AF.3070503@gmx.de> <20041203104828.GJ10492@suse.de> <41B04D8A.7060707@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <41B04D8A.7060707@gmx.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 03 2004, Prakash K. Cheemplavam wrote: > Jens Axboe schrieb: > >On Fri, Dec 03 2004, Prakash K. Cheemplavam wrote: > > > >>>But at least this patch lets you set slice_sync and slice_async > >>>seperately, if you want to experiement. > >> > >>An idea, which values I should try? > > > > > >Just see if the default ones work (or how they work :-) > > > >>BTW, I just did my little test on the ide drive and it shows the same > >>problem, so it is not sata / libata related. > > > > > >Single read/writer case works fine here for me, about half the bandwidth > >for each. Please show some vmstats for this case, too. Right now I'm not > >terribly interested in problems with raid alone, as I can poke holes in > >that. If the single drive case is correct, then we can focus on raid. > > I have not enough space to perform this test on the ide drive, so I did > it on the sata (single disk). The patch doesn't seem to be better. (But > on the other hand I haven't tested you first version on single disk.) At > least it still doesn't look good enough in my eyes. > > procs -----------memory---------- ---swap-- -----io---- --system-- > ----cpu---- > r b swpd free buff cache si so bi bo in cs us > sy id wa > 1 3 2704 5368 1528 906540 0 4 2176 24068 1245 743 0 > 7 0 93 > 0 3 2704 5432 1532 906252 0 0 5072 28160 1277 782 1 > 8 0 91 > 0 5 2704 5688 1532 906080 0 0 9280 4524 1309 842 1 > 10 0 89 > 1 3 2704 5232 1544 906208 0 0 6404 76388 1285 716 1 > 14 0 85 > 0 3 2704 5496 1544 906524 0 0 8328 26624 1301 856 1 > 8 0 91 > 0 3 2704 5512 1528 906636 0 0 9484 22016 1302 883 1 > 8 0 91 > 0 3 2704 5816 1500 906296 0 0 5508 10288 1270 749 1 > 9 0 90 > 0 4 2704 5620 1488 906608 0 0 3076 19920 1267 818 0 > 13 0 87 > 1 4 2704 5684 1456 906432 0 0 3204 18432 1252 704 1 > 8 0 91 > 1 3 2704 5504 1408 906168 0 0 5252 28672 1279 777 1 > 14 0 85 > 0 4 2704 5120 1404 906296 0 0 8968 16384 1351 876 1 > 9 0 90 > 0 4 2704 5364 1404 905620 0 0 5252 26112 1339 835 1 > 14 0 85 > 0 4 2704 5600 1432 905036 0 0 1468 15876 1312 741 2 > 8 0 90 > 1 4 2704 5556 1424 904704 0 0 1664 26112 1243 714 1 > 10 0 89 > 0 4 2704 5492 1428 904100 0 0 1412 31232 1253 760 1 > 15 0 84 > 0 4 2704 5568 1432 903456 0 0 1668 29696 1253 703 1 > 14 0 85 > 1 4 2704 5620 1408 902980 0 0 1280 28672 1248 732 0 > 14 0 86 > 0 4 2704 5236 1404 902888 0 0 2180 28704 1252 705 1 > 11 0 88 > 0 4 2704 5632 1388 902180 0 0 1536 28160 1251 731 1 > 11 0 88 > 0 3 2704 5120 1356 905968 0 0 384 57896 1257 751 1 > 14 0 85 Try increasing slice_sync and idle, just for fun. > What I don't like about the time sliced cfq (first version as well) is > that I don't get good sustained rate anymore if I have only one writer > and nothing else. IIRC with plain cfq I at least got near to maximum > throughput (40-50mb/sec) now it oscillates much more. I have to recheck > with plain cfq though. It might be ext3 related... > > 0 2 2684 7016 9384 900664 0 0 0 59128 1217 576 1 > 7 0 92 > 1 1 2684 5160 9368 898660 0 0 0 12300 1239 4861 1 > 60 0 39 > 0 3 2684 5532 9364 896360 0 0 0 18684 1246 1723 1 > 48 0 51 > 0 3 2684 5596 9364 896616 0 0 0 24576 1246 686 1 That's a bug, I've noticed that too. Sustained write rate for a single thread is somewhat lower than it should be, it's on my todo to investigate. -- Jens Axboe