Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757233Ab2HVGBD (ORCPT ); Wed, 22 Aug 2012 02:01:03 -0400 Received: from cantor2.suse.de ([195.135.220.15]:33655 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757172Ab2HVGA4 (ORCPT ); Wed, 22 Aug 2012 02:00:56 -0400 Date: Wed, 22 Aug 2012 16:00:25 +1000 From: NeilBrown To: Yuanhan Liu Cc: Fengguang Wu , Li Shaohua , "Theodore Ts'o" , Marti Raudsepp , Kernel hackers , ext4 hackers , maze@google.com, "Shi, Alex" , linux-fsdevel@vger.kernel.org, linux RAID Subject: Re: ext4 write performance regression in 3.6-rc1 on RAID0/5 Message-ID: <20120822160025.272188d1@notabene.brown> In-Reply-To: <20120822035702.GF2570@yliu-dev.sh.intel.com> References: <20120816024654.GB3781@thunk.org> <20120816111051.GA16036@localhost> <20120816152513.GA31346@thunk.org> <20120817060915.GB28786@localhost> <20120817134039.GB11439@thunk.org> <20120817142526.GA1059@localhost> <20120822035702.GF2570@yliu-dev.sh.intel.com> X-Mailer: Claws Mail 3.7.10 (GTK+ 2.24.7; x86_64-suse-linux-gnu) Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/doLWNd9A289=bYVeFpiGDTq"; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2081 Lines: 58 --Sig_/doLWNd9A289=bYVeFpiGDTq Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Wed, 22 Aug 2012 11:57:02 +0800 Yuanhan Liu wrote: > =20 > -#define NR_STRIPES 256 > +#define NR_STRIPES 1024 Changing one magic number into another magic number might help your case, b= ut it not really a general solution. Possibly making sure that max_nr_stripes is at least some multiple of the chunk size might make sense, but I wouldn't want to see a very large multip= le. I thing the problems with RAID5 are deeper than that. Hopefully I'll figure out exactly what the best fix is soon - I'm trying to look into it. I don't think the size of the cache is a big part of the solution. I think correct scheduling of IO is the real answer. Thanks, NeilBrown --Sig_/doLWNd9A289=bYVeFpiGDTq Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQIVAwUBUDR1gznsnt1WYoG5AQIvMBAAnwqYNlar29oqFwn2sT2XzxABU10uA6SW px7PJihjVfckygzmPTIibCXb7CdDnKUflXvdTi6YP+ZUEjAmbKVg4OQwkkpZcFoz Xevjdk+SyvSAYZFpiZFqgTpWV8XySW1HO8hfC8aagB3mEKYwd7pLaT0SF5Arer9P e91hUF3SR4Kvytoig45Ucf6KiXHBghbJ6oU2ARGFKWLv4yrOdR/WKs8z9nvGmDHL HMvXY2FONYtxevJ1nWPUp1/gk0cbkpfd/qrZhGopKok/ezQ6CDm4/WpQZZ04dYF9 cQ0ML57fJT8gR9deSIHKyiu89xVgItFoa5YQpa7gZMyk/9Cr1bierN4OCe8YDV2E 9gydeFhw1kbWDUEotPhr5Tk2qazjZg1Kt26Ea0zxBetJNX1jwTPaRnsPFyUMsGCj WUYQ3pBLLUrcec3kJcVz77+HN78AtvoxDE/ZKC35OrlAU0Lh5T3qJ8dThx31jM8C wAqABoqPDeqBUKCe+OA7SRxugvXrpolZ5JH+mGywl3Cp1PHQ7J4G0tHCImHLme+r 9gMrj6uCVacof/W+g+of0n2fKYC1AekxrRcyRXmzZi4AEla06kCy+DOv0ipb99if FaJORbwfZjcd3dOKp+jZg+6UFKWiZ+Clhs5muS2ejkVlagcI/ByP6W53R6EsA8Ds Bei+hDYJNEw= =6+qx -----END PGP SIGNATURE----- --Sig_/doLWNd9A289=bYVeFpiGDTq-- -- 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/