From owner-freebsd-scsi Mon Oct 25 5:40:47 1999 Delivered-To: freebsd-scsi@freebsd.org Received: from post2.fast.net (post2.fast.net [198.69.204.22]) by hub.freebsd.org (Postfix) with ESMTP id D144215034 for ; Mon, 25 Oct 1999 05:40:44 -0700 (PDT) (envelope-from Michael.Sinz@sinz.org) Received: from vixen.sinz.org (maxtnt08-abe-4.fast.net [209.92.13.4]) by post2.fast.net (8.9.1/8.8.5) with ESMTP id IAA23885; Mon, 25 Oct 1999 08:40:31 -0400 (EDT) Received: from Shepard (shepard.sinz.org [192.168.1.2]) by vixen.sinz.org (8.9.3/8.9.3/Sinz.org) with SMTP id IAA28752; Mon, 25 Oct 1999 08:39:57 -0400 Message-Id: <199910251239.IAA28752@vixen.sinz.org> From: "Michael Sinz" To: "Geoff Buckingham" Cc: "Gerard Roudier" , "Mike Sinz" , "Randell Jesup" , "scsi@FreeBSD.ORG" Date: Mon, 25 Oct 1999 08:40:43 -0400 Reply-To: "Michael Sinz" X-Mailer: Sinz.ORG MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Subject: Re: FreeBSD 3.2 / Slow SCSI Dell PowerEdge 4300 Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Mon, 25 Oct 1999 10:58:47 +0100, Geoff Buckingham wrote: >On Wed, Oct 20, 1999 at 10:01:46AM -0400, Michael Sinz wrote: >> >> IMHO: >> For a general purpose server, one must assume that the special case of >> the I/O working out to be single threaded will not happen. Multiple things >> will be going on and the working set will be larger than the cache size. >> A bit of overhead added to the "simple" cases will make the general >> operation better. Benchmarks, however, may well show this as slower >> since some extra overhead had to be added. Benchmarks would need to >> become much more complex in order to show the real benefit or lack of >> benefit for any one technique. >> >Which brings us back to the question as to wether or not disabling TAGs for >WDE * is the correct thing to do? IMHO it is not. For the general case I would say that disabling TAGS is not worth the few specific case performance improvements (most of which are benchmark-only) -- Michael Sinz -- Director of Research & Development, NextBus Inc. mailto:michael.sinz@nextbus.com --------- http://www.nextbus.com My place on the web ---> http://www.users.fast.net/~michael_sinz To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message