From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ric Wheeler Subject: Re: Slower write performance in RHEL6 Date: Tue, 26 Jul 2011 07:38:20 -0400 Message-ID: <4E2EA72C.7030109@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:58131 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753299Ab1GZLiY (ORCPT ); Tue, 26 Jul 2011 07:38:24 -0400 In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Li Liu Cc: linux-scsi@vger.kernel.org On 07/26/2011 07:22 AM, Li Liu wrote: > Dear all, > > In RHEL6(linux-2.6.32-71.el6), I added some codes in > scsi_softirq_done to check the result of execute scsi commands: > WRITE_6, WRITE_10, WRITE_12, WRITE_16 when I executed "dd if=/dev/zero > of=/dev/xda bs=64k count=10000". I found a lot of write error messages > in scsi_softirq_done, the disposition(variable) was ADD_TO_MLQUEUE and > the speed was 78MB/s. > Then I changed MPT_SCSI_CMD_PER_DEV_HIGH from 64 to 32 in > mptscsih_change_queue_depth, the speed was 140MB/s and none error > messages. > * /dev/xda is a scsi disk. > * the scsi host is LSI1064E. > * MPT_SCSI_CMD_PER_DEV_HIGH will be assigned to blk_queue_tag->max_depth. > > My questions are: > Is the TCQ depth limited by hard disk, how can I get the limited? > Why the speed was drop to 78MB/s when MPT_SCSI_CMD_PER_DEV_HIGH was 64? > Could I change MPT_SCSI_CMD_PER_DEV_HIGH to 32 or 16 or 8, Will it > cause any problem? > > Thanks for any ideas. > > Thanks, > Alex Liu When you have a vendor specific issues, it is probably best to raise a ticket with the vendor's support organization.... Thanks! Ric