From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966031AbWKOHok (ORCPT ); Wed, 15 Nov 2006 02:44:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S966049AbWKOHok (ORCPT ); Wed, 15 Nov 2006 02:44:40 -0500 Received: from brick.kernel.dk ([62.242.22.158]:56421 "EHLO kernel.dk") by vger.kernel.org with ESMTP id S966031AbWKOHoj (ORCPT ); Wed, 15 Nov 2006 02:44:39 -0500 Date: Wed, 15 Nov 2006 08:47:21 +0100 From: Jens Axboe To: "Raz Ben-Jehuda(caro)" Cc: linux-aio@kvack.org, Linux Kernel , bcrl@kvack.org, zach.brown@oracle.com Subject: Re: linux io_submit syscall duration Message-ID: <20061115074720.GH23770@kernel.dk> References: <5d96567b0611142339k23e78cc6u19b64052be5cd360@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5d96567b0611142339k23e78cc6u19b64052be5cd360@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 15 2006, Raz Ben-Jehuda(caro) wrote: > Bnejamin hello. > > My name is raz and i have encountered a problem with io_submit. > The maximum duration of a single io_submit operation when > heavily stressing the system with large number of big (1MB) ios, > reaches several hundereds ms. > > I have been profiling it and it seems that the problem is the > file->f_op->aio_read operation, > a call that is made in fs/aio.c when coming from: > sys_io_submit --> > io_submit_one --> > aio_run_iocb --> > *retry > > > The test is initiating several hundered 1MB IOs over a single block device. > > I understand that the assumption made was aio_read is asynchronous and no > delay will occure, but isn't possible to do it in the workqueue context ? This was discussed no more than a week ago on this list, please search the archives for the thread. -- Jens Axboe