From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262125AbULCJoF (ORCPT ); Fri, 3 Dec 2004 04:44:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262131AbULCJoF (ORCPT ); Fri, 3 Dec 2004 04:44:05 -0500 Received: from ns.virtualhost.dk ([195.184.98.160]:58840 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S262125AbULCJn7 (ORCPT ); Fri, 3 Dec 2004 04:43:59 -0500 Date: Fri, 3 Dec 2004 10:43:14 +0100 From: Jens Axboe To: "Prakash K. Cheemplavam" Cc: akpm@osdl.org, linux-kernel@vger.kernel.org, nickpiggin@yahoo.com.au Subject: Re: Time sliced CFQ io scheduler Message-ID: <20041203094314.GF10492@suse.de> References: <20041202130457.GC10458@suse.de> <20041202134801.GE10458@suse.de> <20041202114836.6b2e8d3f.akpm@osdl.org> <20041202195232.GA26695@suse.de> <20041202121938.12a9e5e0.akpm@osdl.org> <41AF94B8.8030202@gmx.de> <20041203070108.GA10492@suse.de> <41B02DFD.9090503@gmx.de> <20041203091840.GD10492@suse.de> <41B03375.4050702@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <41B03375.4050702@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: > > > >>Jens Axboe schrieb: > >> > >>>On Thu, Dec 02 2004, Prakash K. Cheemplavam wrote: > >>> > >> > >>>>0 3 3080 2208 1156 817712 0 0 3592 75624 1326 2289 1 36 > >>>>0 63 > >>>>0 3 3080 2664 1156 818240 0 0 5124 15692 1302 992 1 18 > >>>>0 81 > >>>>0 3 3080 2580 1160 815832 0 0 4356 155792 1375 1064 1 > >>>>39 0 60 > >>>>0 3 3080 2472 1160 817124 0 0 3076 100852 1345 1138 1 > >>>>23 0 76 > >>>>2 4 3080 2836 1148 816228 0 0 3336 100412 1352 1379 1 > >>>>47 0 52 > >>>>0 4 3080 2708 1144 815964 0 0 3844 48908 1343 871 1 25 > >>>>0 74 > >>>>0 3 3080 2748 1152 815984 0 0 3332 71996 1338 843 1 27 > >>>>0 72 > >>> > >>> > >>>Can you try with the patch that is in the parent of this thread? The > >>>above doesn't look that bad, although read performance could be better > >>>of course. But try with the patch please, I'm sure it should help you > >>>quite a lot. > >>> > >> > >>It actually got worse: Though the read rate seems accepteble, it is not, > >>as interactivity is dead while writing. I cannot start porgrammes, other > >>programmes which want to do i/o pretty much hang. This is only while > >>writing. While reading there is no such problem. > > > > > >Interesting, thanks for testing. I'll run some tests here as well, so > >far only the cases mentioned yesterday have been tested. > > BTW, in case it is misread: Above (except the io performance as such) is > no regression: The other schedulers behave the same on my system. Yes, that's what I assumed. Another thing to keep in mind is that even with just a single writer, you could have 3 people doing writeout for you (pdflush for each disk, and the writer itself), while the reader is on its own. This could affect latencies/bandwidth for the reader in not-so pleasant ways. > >You could try and bumb the slice period. But I'll experiment and see > >what happens. What is your test case? > > [slice bumping] Uhm, is it doable via proc? I haven't seen text docs to > your patch and I am not good at kernel code ;-) :-) See my previous mail, it tells you how to do it. -- Jens Axboe