From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Battersby Subject: Re: [PATCH] [SCSI] sym53c8xx: increase sg_tablesize for larger data transfers Date: Thu, 15 Nov 2007 11:38:30 -0500 Message-ID: <473C7606.7050608@cybernetics.com> References: <473C6084.2040700@cybernetics.com> <1195143006.3407.20.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from host06.cybernetics.com ([206.246.200.22]:4328 "EHLO mail.cybernetics.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1757953AbXKOQi1 (ORCPT ); Thu, 15 Nov 2007 11:38:27 -0500 In-Reply-To: <1195143006.3407.20.camel@localhost.localdomain> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Matthew Wilcox , linux-scsi@vger.kernel.org James Bottomley wrote: > On Thu, 2007-11-15 at 10:06 -0500, Tony Battersby wrote: > >> This patch increases the sg_tablesize for sym53c8xx from 96 to 128, >> which enables commands to transfer larger amounts of data (e.g. 512 KB >> instead of 384 KB, assuming 4 KB non-adjacent pages). >> >> In the current design of sym53c8xx, SYM_CONF_MAX_SG must be set low >> enough so that (sym_fw1.a_size <= PAGE_SIZE) && (sym_fw2.a_size <= >> PAGE_SIZE). With SYM_CONF_MAX_SG == 128, sym_fw1.a_size == 3940 and >> sym_fw2.a_size == 3576 (plus or minus a few bytes depending on other >> configuration options). The a_size values increase by 16 for every >> additional sg vector, so SYM_CONF_MAX_SG cannot be set much higher than >> 128 without making more intrusive changes. >> > > This has been suggested before. I thought the problem was there were > some cards of the 875 ilk that choke on a sg table larger than 96? If I > recall the conversation correctly, the claim was made, but no-one > managed to turn up the errata that showed it. > > James > > > I will try to get ahold of some 875's to test. Tony