From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: Patch: [Open-FCoE] Revert commit 3e22760d4db6fd89e0be46c3d132390a251da9c6 due to performance issues Date: Fri, 14 Oct 2016 16:39:13 -0400 Message-ID: References: <209207528.804499.1475931430678.JavaMail.zimbra@redhat.com> <2d30ad34-7a5e-b2ba-05f4-b0d831944f4c@suse.de> <1476197489.4019.68.camel@localhost.localdomain> <1476286016.4019.105.camel@localhost.localdomain> <000ebf71-9b7a-e6f6-ff8f-0f06eeef64fa@suse.de> <1564904000.1465519.1476321625269.JavaMail.zimbra@redhat.com> <2049046384.1533310.1476362610308.JavaMail.zimbra@redhat.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from userp1040.oracle.com ([156.151.31.81]:48343 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754974AbcJNUjZ (ORCPT ); Fri, 14 Oct 2016 16:39:25 -0400 In-Reply-To: <2049046384.1533310.1476362610308.JavaMail.zimbra@redhat.com> (Laurence Oberman's message of "Thu, 13 Oct 2016 08:43:30 -0400 (EDT)") Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Laurence Oberman Cc: Hannes Reinecke , Ewan Milne , Bud Brown , Linux SCSI Mailinglist , "Curtis Taylor (cjt@us.ibm.com)" , fcoe-devel@open-fcoe.org >>>>> "Laurence" == Laurence Oberman writes: Laurence> This patch reverts commit Laurence> 3e22760d4db6fd89e0be46c3d132390a251da9c6. Laurence> This revert came about because of efforts by Ewan Milne, Laurence> Curtis Taylor and I. In researching this issue, significant Laurence> performance issues were seen on large CPU count systems using Laurence> the software FCOE stack. Hannes also weighed in. Laurence> The same was not apparent on much smaller low count CPU Laurence> systems. The behavior introduced by commit Laurence> 3e22760d4db6fd89e0be46c3d132390a251da9c6 lands sup with large Laurence> count CPU systems seeing continual blk_requeue_request() calls Laurence> due to ML_QUEUE_HOST_BUSY. Applied to 4.10/scsi-queue. -- Martin K. Petersen Oracle Linux Engineering