From owner-freebsd-arch@FreeBSD.ORG Wed Mar 16 03:19:46 2005 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D02DE16A4CF for ; Wed, 16 Mar 2005 03:19:46 +0000 (GMT) Received: from duchess.speedfactory.net (duchess.speedfactory.net [66.23.201.84]) by mx1.FreeBSD.org (Postfix) with SMTP id 1233543D49 for ; Wed, 16 Mar 2005 03:19:46 +0000 (GMT) (envelope-from ups@tree.com) Received: (qmail 17458 invoked by uid 89); 16 Mar 2005 03:19:44 -0000 Received: from duchess.speedfactory.net (66.23.201.84) by duchess.speedfactory.net with SMTP; 16 Mar 2005 03:19:44 -0000 Received: (qmail 17440 invoked by uid 89); 16 Mar 2005 03:19:44 -0000 Received: from unknown (HELO palm.tree.com) (66.23.216.49) by duchess.speedfactory.net with SMTP; 16 Mar 2005 03:19:44 -0000 Received: from [127.0.0.1] (localhost.tree.com [127.0.0.1]) by palm.tree.com (8.12.10/8.12.10) with ESMTP id j2G3Jhw6093534; Tue, 15 Mar 2005 22:19:44 -0500 (EST) (envelope-from ups@tree.com) From: Stephan Uphoff To: Peter Wemm In-Reply-To: <200503151743.49851.peter@wemm.org> References: <20050303074242.GA14699@VARK.MIT.EDU> <20050303153505.GA16964@VARK.MIT.EDU> <200503151743.49851.peter@wemm.org> Content-Type: text/plain Message-Id: <1110943183.29804.42558.camel@palm> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Tue, 15 Mar 2005 22:19:43 -0500 Content-Transfer-Encoding: 7bit cc: David Schultz cc: "freebsd-arch@freebsd.org" Subject: Re: Removing kernel thread stack swapping X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Mar 2005 03:19:47 -0000 On Tue, 2005-03-15 at 20:43, Peter Wemm wrote: > On Thursday 03 March 2005 07:35 am, David Schultz wrote: > > On Thu, Mar 03, 2005, John Baldwin wrote: > [..] > > > Hence, don't kill this whole feature just because someone is too > > > lazy to fix a bug. > > > > Fair enough. I'll defer to you on the extent of the problem. > > David seemed to think that it was more widespread. (BTW, does > > *anyone* know what the PHOLD() in kern_physio is for? Is it a > > holdover from when the PCB was in struct user?) > > I've wondered about this myself in the past. I went looking once and > discovered that it never did anything that I could find. I believe it > is a case of 'because it was always done that way' or because the > pseudocode in the Bach or bsd books had it. There is certainly no > functional need for it in FreeBSD. kern_physio prevents chunks of memory needed for IO from being paged out. Swapping out a thread in kern_physio will prevent it from releasing the resources soon. With minphys > stack size I think PHOLD() is still a good idea. Stephan