From owner-freebsd-arch Wed Mar 21 14:33:20 2001 Delivered-To: freebsd-arch@freebsd.org Received: from mail.wgate.com (mail.wgate.com [38.219.83.4]) by hub.freebsd.org (Postfix) with ESMTP id 7E8A337B71A; Wed, 21 Mar 2001 14:33:17 -0800 (PST) (envelope-from rjesup@wgate.com) Received: from jesup.eng.tvol.net ([10.32.2.26]) by mail.wgate.com with SMTP (Microsoft Exchange Internet Mail Service Version 5.5.2653.13) id GN5YZGFQ; Wed, 21 Mar 2001 17:33:20 -0500 Reply-To: Randell Jesup To: Mike Smith , arch@FreeBSD.ORG Subject: Re: remind me again, why is MAXPHYS only 128k ? References: <89046.985209441@critter> <200103212138.f2LLc8a21690@earth.backplane.com> From: Randell Jesup Date: 21 Mar 2001 17:34:44 -0500 In-Reply-To: Matt Dillon's message of "Wed, 21 Mar 2001 13:38:08 -0800 (PST)" Message-ID: User-Agent: Gnus/5.0807 (Gnus v5.8.7) Emacs/20.7 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Matt Dillon writes: > When I last discussed MAXPHYS with people the issue that was predominant > was the b_pages[] array embedded in the struct buf and the pages[] arrays > declared in the VM paging code. I was worried that an increased MAXPHYS > eating too much kernel stack and too much kernel memory. We also have > the issue of the physical buffers (pbufs) reserving VM space permanently. > If you increase MAXPHYS you quickly start to hit kernel VM limitations. I seem to remember we thought that those could become pointers to arrays instead of in-line; or at least optionally so. CHeck the archives on freebsd.org for -arch; it wasn't that long ago. -- Randell Jesup, Worldgate Communications, ex-Scala, ex-Amiga OS team ('88-94) rjesup@wgate.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message