From owner-freebsd-arch Wed Mar 21 13:26:29 2001 Delivered-To: freebsd-arch@freebsd.org Received: from feral.com (feral.com [192.67.166.1]) by hub.freebsd.org (Postfix) with ESMTP id E25BC37B71D; Wed, 21 Mar 2001 13:26:26 -0800 (PST) (envelope-from mjacob@feral.com) Received: from zeppo.feral.com (IDENT:mjacob@zeppo [192.67.166.71]) by feral.com (8.9.3/8.9.3) with ESMTP id NAA11370; Wed, 21 Mar 2001 13:26:31 -0800 Date: Wed, 21 Mar 2001 13:26:21 -0800 (PST) From: Matthew Jacob Reply-To: mjacob@feral.com To: Mike Smith Cc: Poul-Henning Kamp , arch@FreeBSD.ORG Subject: Re: remind me again, why is MAXPHYS only 128k ? In-Reply-To: <200103212111.f2LLBSh01790@mass.dis.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Wed, 21 Mar 2001, Mike Smith wrote: > > > > Are there any roadblocks for increasing MAXPHYS as a tweakable these > > days, or is it still an "do not alter or ELSE..." #define ? > > There isn't much hardware out there that can do anything useful with an > I/O larger than 128k. There was also a lengthy discussion on I/O > saturation a little while back; the short answer is just that making it > larger doesn't win anything significant, and may cause unacceptable > latencies in some cases. That was maybe only one person's opinion. It was not a consensus by any means. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message