From owner-svn-src-all@FreeBSD.ORG Sat Mar 17 23:50:00 2012 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 88D881065670; Sat, 17 Mar 2012 23:50:00 +0000 (UTC) (envelope-from alc@rice.edu) Received: from mh1.mail.rice.edu (mh1.mail.rice.edu [128.42.201.20]) by mx1.freebsd.org (Postfix) with ESMTP id 557098FC08; Sat, 17 Mar 2012 23:50:00 +0000 (UTC) Received: from mh1.mail.rice.edu (localhost.localdomain [127.0.0.1]) by mh1.mail.rice.edu (Postfix) with ESMTP id DB231291E62; Sat, 17 Mar 2012 18:49:52 -0500 (CDT) Received: from mh1.mail.rice.edu (localhost.localdomain [127.0.0.1]) by mh1.mail.rice.edu (Postfix) with ESMTP id CF0E8297615; Sat, 17 Mar 2012 18:49:52 -0500 (CDT) X-Virus-Scanned: by amavis-2.6.4 at mh1.mail.rice.edu, auth channel Received: from mh1.mail.rice.edu ([127.0.0.1]) by mh1.mail.rice.edu (mh1.mail.rice.edu [127.0.0.1]) (amavis, port 10026) with ESMTP id DRPBASXLP7LB; Sat, 17 Mar 2012 18:49:52 -0500 (CDT) Received: from adsl-216-63-78-18.dsl.hstntx.swbell.net (adsl-216-63-78-18.dsl.hstntx.swbell.net [216.63.78.18]) (using TLSv1 with cipher RC4-MD5 (128/128 bits)) (No client certificate requested) (Authenticated sender: alc) by mh1.mail.rice.edu (Postfix) with ESMTPSA id F21BF291DF5; Sat, 17 Mar 2012 18:49:51 -0500 (CDT) Message-ID: <4F65231F.1000101@rice.edu> Date: Sat, 17 Mar 2012 18:49:51 -0500 From: Alan Cox User-Agent: Mozilla/5.0 (X11; FreeBSD i386; rv:8.0) Gecko/20111113 Thunderbird/8.0 MIME-Version: 1.0 To: Nathan Whitehorn References: <201203172204.q2HM4xBH088986@svn.freebsd.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Alan Cox , svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r233097 - head/sys/amd64/amd64 X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 17 Mar 2012 23:50:00 -0000 On 03/17/2012 17:14, Nathan Whitehorn wrote: > > > On Mar 17, 2012, at 5:04 PM, Alan Cox wrote: > >> Author: alc >> Date: Sat Mar 17 22:04:58 2012 >> New Revision: 233097 >> URL: http://svn.freebsd.org/changeset/base/233097 >> >> Log: >> With the changes over the past year to how accesses to the page's dirty >> field are synchronized, there is no need for pmap_protect() to acquire >> the page queues lock unless it is going to access the pv lists. >> >> Reviewed by: kib > > Under what circumstances does the page queue lock actually have to be > held? You need it when you are manipulating the pvo_vlink lists. That said, we are at the point where the PPC/AIM pmap could define its own PVO list mutex and not (ab)use the page queues mutex for this purpose. Just do a straightforward, mechanical substitution, and you should be fine. > It looks like from this that I can remove the page queue lock from the > PPC/AIM pmap_protect() completely, but I don't have a good sense of it. Yes, you can this instant remove the acquisition and release of the page queues lock from this function.