Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269743AbUJMOdi (ORCPT ); Wed, 13 Oct 2004 10:33:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269742AbUJMOdh (ORCPT ); Wed, 13 Oct 2004 10:33:37 -0400 Received: from mx1.redhat.com ([66.187.233.31]:40111 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S269731AbUJMOaQ (ORCPT ); Wed, 13 Oct 2004 10:30:16 -0400 From: Jeff Moyer MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16749.15265.475571.767534@segfault.boston.redhat.com> Date: Wed, 13 Oct 2004 10:28:49 -0400 To: Pavel Machek Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, sct@redhat.com Subject: Re: [patch rfc] towards supporting O_NONBLOCK on regular files In-Reply-To: <20041003194831.GB3089@openzaurus.ucw.cz> References: <16733.50382.569265.183099@segfault.boston.redhat.com> <20041003194831.GB3089@openzaurus.ucw.cz> X-Mailer: VM 7.14 under 21.4 (patch 13) "Rational FORTRAN" XEmacs Lucid Reply-To: jmoyer@redhat.com 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? Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1172 Lines: 27 ==> Regarding Re: [patch rfc] towards supporting O_NONBLOCK on regular files; Pavel Machek adds: pavel> Hi! >> This patch makes an attempt at supporting the O_NONBLOCK flag for >> regular files. It's pretty straight-forward. One limitation is that we >> still call into the readahead code, which I believe can block. However, >> if we don't do this, then an application which only uses non-blocking >> reads may never get it's data. pavel> This looks very nice. Does it mean that aio and friends are pavel> instantly obsolete? I dont' think so. This only addresses the read() path, for one. Plus, in it's current form, it will not perform any I/O if the data is not present. So, you will need another thread/process to do kick off the I/O. pavel> Does it have comparable performance to aio? I haven't run any tests. One advantage this has to current aio is that it can operate without O_DIRECT. -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/