From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262149AbULCKpU (ORCPT ); Fri, 3 Dec 2004 05:45:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262150AbULCKpU (ORCPT ); Fri, 3 Dec 2004 05:45:20 -0500 Received: from imap.gmx.net ([213.165.64.20]:49073 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S262149AbULCKpL (ORCPT ); Fri, 3 Dec 2004 05:45:11 -0500 X-Authenticated: #4512188 Message-ID: <41B043AF.3070503@gmx.de> Date: Fri, 03 Dec 2004 11:45:03 +0100 From: "Prakash K. Cheemplavam" User-Agent: Mozilla Thunderbird 0.9 (X11/20041114) X-Accept-Language: de-DE, de, en-us, en MIME-Version: 1.0 To: Jens Axboe CC: Andrew Morton , Linux Kernel , nickpiggin@yahoo.com.au Subject: Re: Time sliced CFQ io scheduler References: <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> <20041203012645.21377669.akpm@osdl.org> <20041203093903.GE10492@suse.de> <41B03722.5090001@gmx.de> <20041203103130.GH10492@suse.de> <20041203103828.GI10492@suse.de> In-Reply-To: <20041203103828.GI10492@suse.de> X-Enigmail-Version: 0.89.0.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigBFD25EDFFDAC80FECD8D362F" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigBFD25EDFFDAC80FECD8D362F Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Jens Axboe schrieb: > On Fri, Dec 03 2004, Jens Axboe wrote: > >>Funky. It looks like another case of the io scheduler being at the wrong >>place - if raid sends dependent reads to different drives, it screws up >>the io scheduling. The right way to fix that would be to io scheduler >>before raid (reverse of what we do now), but that is a lot of work. A >>hack would be to try and tie processes to one md component for periods >>of time, sort of like cfq slicing. > > > It makes sense to split the slice period for sync and async requests, > since async requests usually get a lot of requests queued in a short > period of time. Might even make sense to introduce a slice_rq value as > well, limiting the number of requests queued in a given slice. > > 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? In generell I rather have the impression the problem I am experiencing is not the problem of the io scheduler alone or why do all show the same problem? BTW, I just did my little test on the ide drive and it shows the same problem, so it is not sata / libata related. Prakash --------------enigBFD25EDFFDAC80FECD8D362F Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.6 (GNU/Linux) iD8DBQFBsEO1xU2n/+9+t5gRAth9AJ9LAQVDMif2Uuh6iKHR/jDFqD6HqgCgyPy3 CDS50cq/CjvJlliCVbRUAaI= =X6nQ -----END PGP SIGNATURE----- --------------enigBFD25EDFFDAC80FECD8D362F--