From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH 1/1] be2iscsi: Fixes for powerpc compile Date: Thu, 10 Sep 2009 17:15:40 +0000 Message-ID: <1252602940.11956.108.camel@mulgrave.site> References: <20090909191520.fb9e5110@mailhost.serverengines.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from cantor.suse.de ([195.135.220.2]:51583 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750714AbZIJRPp (ORCPT ); Thu, 10 Sep 2009 13:15:45 -0400 In-Reply-To: <20090909191520.fb9e5110@mailhost.serverengines.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Jayamohan Kalickal Cc: Mike Christie , linux-scsi@vger.kernel.org, sfr@canb.auug.org.au On Wed, 2009-09-09 at 12:15 -0700, Jayamohan Kalickal wrote: > Implementing pci_pool is not a problem. But, my experience with this chip > (or for that matter any chip that can do huge IOPS ,say, more then 600 -700 KIOPS), > every line of code on the hot path would have an impact and hence I strive to > move it out of the hot path. > > The code is not yet optimized for speed yet but I definitely want to push whatever > I can to init time from the IO path. I'll fold in the patch as is because we urgently need a fix for the virt_to_bus() problem. pci_pool was designed to allow for good IOP throughput (that's why lpfc is using it). The pci_alloc_consistent() you've chosen often only allocates at the page level, so it can be hugely wasteful of resources; plus coherent memory is a precious resource on some platforms, so I can see you running out on them. Could you at least try a pci_pool implementation ... if it really turns out to be a performance problem we can keep the current implementation despite the potential resource issues. Thanks, James