Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752709Ab0BWRiv (ORCPT ); Tue, 23 Feb 2010 12:38:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:19497 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751037Ab0BWRit (ORCPT ); Tue, 23 Feb 2010 12:38:49 -0500 From: Jeff Moyer To: Oliver Neukum Cc: GeunSik Lim , linux-kernel@vger.kernel.org Subject: Re: question on readahead and sync mounting References: <201002230032.18705.oliver@neukum.org> <49b7c2351002221548ma5b8e81m80ac4b60a6eb9d9d@mail.gmail.com> <201002230059.09390.oliver@neukum.org> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Tue, 23 Feb 2010 12:38:44 -0500 In-Reply-To: <201002230059.09390.oliver@neukum.org> (Oliver Neukum's message of "Tue, 23 Feb 2010 00:59:09 +0100") Message-ID: User-Agent: Gnus/5.110011 (No Gnus v0.11) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1002 Lines: 24 Oliver Neukum writes: > Am Dienstag, 23. Februar 2010 00:48:39 schrieben Sie: >> Please, Refer to below articles to understand readahead essentially. >> >> http://lwn.net/Articles/235164/ (On-demand readahead by corbet) >> http://kernelnewbies.org/Linux_2_6_23#head-102af265937262a7a21766ae58fddc1a29a5d8d7( >> On-demand read-ahead on Linux 2.6.23) > > OK, I am looking for a way to make sure read requests on a SCSI drive > actually hit the bus after a certain event. Is there a way to do this without > tossing away the whole cache? I'm not sure I understand what you're asking, but it sounds like you want to do an O_DIRECT read. Open the file with O_DIRECT, then pass a properly-aligned buffer to the read(2) call. Cheers, Jeff -- 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/