From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chandra Seetharaman Subject: [PATCH 0/3] scsi_dh: Make scsi_dh_activate asynchronous Date: Mon, 27 Apr 2009 19:52:30 -0700 Message-ID: <20090428025230.11108.88559.sendpatchset@chandra-ubuntu> Return-path: Received: from e35.co.us.ibm.com ([32.97.110.153]:59871 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752191AbZD1Cvi (ORCPT ); Mon, 27 Apr 2009 22:51:38 -0400 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e35.co.us.ibm.com (8.13.1/8.13.1) with ESMTP id n3S2k1Al007320 for ; Mon, 27 Apr 2009 20:46:01 -0600 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n3S2pbW5079904 for ; Mon, 27 Apr 2009 20:51:37 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n3S2pbDl002806 for ; Mon, 27 Apr 2009 20:51:37 -0600 Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: linux-scsi@vger.kernel.org Cc: dm-devel@redhat.com, babu.moger@lsi.com, michaelc@cs.wisc.edu, Chandra Seetharaman Hello All, Currently, device handlers process path activation in series. This leads to a lot of time delay when more than 100 luns are involved. For example, with lsi rdac 100+ luns take about 12-15 minutes. This was found by Moger Babu of LSI. This time delay can be avoided if we can do the activations asynchronously. By making scsi_dh_activate() async, we can give the device handlers an oppurtunity to decide on how to send the device activation down the wire to make the turn around time faster. They can send the commands asynchronously or send them in batches. I brought up this issue on th emailing list few days back (http://marc.info/?l=linux-scsi&m=123888063818755&w=2). This set of patches applies cleanly on 2.6.30-rc3 and is tested on the same. Please review and provide comments. This set of patched adds asynchronous support only to rdac handler. WIll be sending patches to support other handlers too. Thanks & Regards, chandra