Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932336AbZGOUvr (ORCPT ); Wed, 15 Jul 2009 16:51:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932323AbZGOUvr (ORCPT ); Wed, 15 Jul 2009 16:51:47 -0400 Received: from cantor2.suse.de ([195.135.220.15]:50005 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932303AbZGOUvq (ORCPT ); Wed, 15 Jul 2009 16:51:46 -0400 Date: Wed, 15 Jul 2009 22:52:20 +0200 From: Kurt Garloff To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [RESEND] [PATCH] readahead:add blk_run_backing_dev Message-ID: <20090715205220.GL31657@tpkurt2.suse.de> Mail-Followup-To: Kurt Garloff , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <4A4DE3C1.5080307@vlnb.net> <4A51DC0A.10302@vlnb.net> <4A5238EC.1070505@vlnb.net> <4A5395FD.2040507@vlnb.net> <4A5493A8.2000806@vlnb.net> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="4XBiSqiiHCIj6zoM" Content-Disposition: inline In-Reply-To: <4A5493A8.2000806@vlnb.net> X-Operating-System: Linux 2.6.27.23-0.1-default x86_64 X-PGP-Info: on http://www.garloff.de/kurt/mykeys.pgp X-PGP-Key: 1024D/1C98774E Organization: SUSE Linux Products GmbH (a Novell company), Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg) User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1328 Lines: 44 --4XBiSqiiHCIj6zoM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, On Wed, Jul 08, 2009 at 04:40:08PM +0400, Vladislav Bolkhovitin wrote: > I've also long ago noticed that reading data from block devices is slower= =20 > than from files from mounted on those block devices file systems. Can=20 > anybody explain it? Brainstorming: - block size (reads on the block dev might be done with smaller size) - readahead (do we use the same RA algo for block devs) - page cache might be better optimized than buffer cache? Just guesses from someone that has not looked into that area of the kernel for a while, so take it with a grain of salt. Cheers, --=20 Kurt Garloff, VP OPS Partner Engineering -- Novell Inc. --4XBiSqiiHCIj6zoM Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) iD8DBQFKXkGExmLh6hyYd04RAmIdAKDO25MtI+jgPE09QrhDPWmUFkLPhwCfbrZO 7h8ZtYqALUktKQZEkthjf10= =7dKY -----END PGP SIGNATURE----- --4XBiSqiiHCIj6zoM-- -- 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/