From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chandra Seetharaman Subject: Re: [dm-devel] [PATCH 4/7] scsi_dh: add EMC Clariion device handler Date: Tue, 22 Apr 2008 16:45:53 -0700 Message-ID: <1208907953.1025.235.camel@chandra-ubuntu> References: <20080416011818.19580.41106.sendpatchset@chandra-ubuntu> <20080416011842.19580.92056.sendpatchset@chandra-ubuntu> <4806294C.9090703@cs.wisc.edu> <1208390384.1025.40.camel@chandra-ubuntu> <48078571.9040806@cs.wisc.edu> <1208898559.1025.191.camel@chandra-ubuntu> <480E5D08.3000905@cs.wisc.edu> Reply-To: sekharan@us.ibm.com Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from e1.ny.us.ibm.com ([32.97.182.141]:36833 "EHLO e1.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752425AbYDVXpY (ORCPT ); Tue, 22 Apr 2008 19:45:24 -0400 Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by e1.ny.us.ibm.com (8.13.8/8.13.8) with ESMTP id m3MNjLxN025231 for ; Tue, 22 Apr 2008 19:45:21 -0400 Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay02.pok.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id m3MNjLWY239594 for ; Tue, 22 Apr 2008 19:45:21 -0400 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m3MNjKWZ028980 for ; Tue, 22 Apr 2008 19:45:21 -0400 In-Reply-To: <480E5D08.3000905@cs.wisc.edu> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Mike Christie Cc: linux-scsi@vger.kernel.org, device-mapper development , andmike@us.ibm.com, asson_ronald@emc.com, James.Bottomley@HansenPartnership.com, Benoit_Arthur@emc.com, jens.axboe@oracle.com, agk@redhat.com, berthiaume_wayne@emc.com On Tue, 2008-04-22 at 16:47 -0500, Mike Christie wrote: > > wait > > ****************************************************** > > Simple Run: > > > > with patchset: 2.6.25-mm1: > > real 3m30.122s real 3m29.746s > > user 0m4.069s user 0m4.099s > > sys 0m14.876s sys 0m14.535s > > ----------------------------------------------- > > Is this just a boot up test or a test just running IO but no > failback/failover? Test running IO but no failover/failback. > > > > > Failover Run: > > > > with patchset: 2.6.25-mm1: > > real 5m18.875s real 5m31.741s > > user 0m4.069s user 0m3.883s > > sys 0m14.838s sys 0m13.822s > > Ehh, I have no idea if this is good or bad. Does it mean it is talking > 13 more seconds to complete? It is taking 13 more seconds without the serialization :) (i.e the old code). > > Have you seen the type of thread on dm-devel or the iscsi list where > people are concerned with getting the time the failure is detected to > the time IO is running on a new path down from something like 10 to 5 I totally agree with you that shaving a second here and a second there has lot of value to the customers. > > seconds. One time the iscsi driver did not implement time2wait correctly > and by fixing it we shaved only 2 seconds off and users were very happy > with the extra 2 seconds. We added the nop timer stuff so we could get > faster failovers. We have the fast io fail tmo so we can speed up the > process even more. Shaving off a second here or there is really nitpicky > and if I were you I would give me the middle finger :) It just seems But, I wouldn't :) > > like people expect better performance from this type of error. > > If my comment is too nitpicky then I am fine with ignoring this for now. > We just have to fix the emc short/long tress pass code then. I added > another EMC guy to the thread so he can ping the other EMC devs to get > going (I had sent them questions on how to handle it and have not got a > response).