From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965904AbWKOHjQ (ORCPT ); Wed, 15 Nov 2006 02:39:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965919AbWKOHjQ (ORCPT ); Wed, 15 Nov 2006 02:39:16 -0500 Received: from py-out-1112.google.com ([64.233.166.183]:16014 "EHLO py-out-1112.google.com") by vger.kernel.org with ESMTP id S965904AbWKOHjP (ORCPT ); Wed, 15 Nov 2006 02:39:15 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:mime-version:content-type:content-transfer-encoding:content-disposition; b=ghpQWDqXpAuBeXTAY8MMQVyojEXyOe8CGs1ipAS2jSQ5jJhSbyyvkodYy2I0Bl81rHaivOoKLxLhPprVQTOeO687swILkJgvF4ncR6TaWShRy4OKDthUTi+QzgeLP6gP/LDNjq9coteudBmwx0n0xv9ejtDzWC0X3fhtYwPXUvI= Message-ID: <5d96567b0611142339k23e78cc6u19b64052be5cd360@mail.gmail.com> Date: Wed, 15 Nov 2006 09:39:14 +0200 From: "Raz Ben-Jehuda(caro)" To: linux-aio@kvack.org, "Linux Kernel" Subject: linux io_submit syscall duration Cc: bcrl@kvack.org, zach.brown@oracle.com MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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 ? would appreciate your help. thank you raz