Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932652AbWKFGml (ORCPT ); Mon, 6 Nov 2006 01:42:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932668AbWKFGmk (ORCPT ); Mon, 6 Nov 2006 01:42:40 -0500 Received: from pop-satin.atl.sa.earthlink.net ([207.69.195.63]:27272 "EHLO pop-satin.atl.sa.earthlink.net") by vger.kernel.org with ESMTP id S932652AbWKFGmk (ORCPT ); Mon, 6 Nov 2006 01:42:40 -0500 Date: Mon, 6 Nov 2006 01:42:32 -0500 (EST) From: Brent Baccala X-X-Sender: baccala@debian.freesoft.org To: Jens Axboe cc: linux-kernel@vger.kernel.org Subject: Re: async I/O seems to be blocking on 2.6.15 In-Reply-To: <20061105121522.GC13555@kernel.dk> Message-ID: References: <20061103122055.GE13555@kernel.dk> <20061103160212.GK13555@kernel.dk> <20061105121522.GC13555@kernel.dk> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1299 Lines: 37 On Sun, 5 Nov 2006, Jens Axboe wrote: > On Fri, Nov 03 2006, Brent Baccala wrote: >> >> Does 7 microseconds seem a bit excessive for an io_submit (and a >> gettimeofday)? > > I guess you mean miliseconds, not microseconds. 7 miliseconds seems way > too long. I repeated your test here, and the 100 submits take 97000 > microseconds here - or 97 miliseconds. So that's a little less than 1 > msec per io_submit. Still pretty big. You can experiment with oprofile > to profile where the kernel spends its time in that period. > > -- > Jens Axboe > Yes, of course, milliseconds. I have enough other problems with this program (measured in minutes, and no mistake that) that I doubt I'll be profiling the kernel any time soon, but thank you for your help. More than anything else, you've made me understand that I can't just fire off a bunch of async requests like I'm tossing peanuts across the table. I've really got to pay attention to what's in that kernel queue and how it gets managed. -bwb Brent Baccala cosine@freesoft.org - 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/