From owner-cvs-src@FreeBSD.ORG Thu Mar 3 13:07:40 2005 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 33B0116A4CE for ; Thu, 3 Mar 2005 13:07:40 +0000 (GMT) Received: from mail22.sea5.speakeasy.net (mail22.sea5.speakeasy.net [69.17.117.24]) by mx1.FreeBSD.org (Postfix) with ESMTP id B631F43D4C for ; Thu, 3 Mar 2005 13:07:39 +0000 (GMT) (envelope-from jhb@FreeBSD.org) Received: (qmail 27360 invoked from network); 3 Mar 2005 13:07:39 -0000 Received: from server.baldwin.cx ([216.27.160.63]) (envelope-sender )AES256-SHA encrypted SMTP for ; 3 Mar 2005 13:07:39 -0000 Received: from [192.168.0.15] (osx.baldwin.cx [192.168.0.15]) (authenticated bits=0) by server.baldwin.cx (8.13.1/8.13.1) with ESMTP id j23D7XtD089469; Thu, 3 Mar 2005 08:07:34 -0500 (EST) (envelope-from jhb@FreeBSD.org) In-Reply-To: <20050303062458.GA15192@cs.rice.edu> References: <200503030241.j232fbCn032297@repoman.freebsd.org> <20050303062458.GA15192@cs.rice.edu> Mime-Version: 1.0 (Apple Message framework v619.2) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <34c3d5c3060ce1ea1be35d9be1198902@FreeBSD.org> Content-Transfer-Encoding: 7bit From: John Baldwin Date: Thu, 3 Mar 2005 08:07:33 -0500 To: Alan Cox X-Mailer: Apple Mail (2.619.2) X-Spam-Status: No, score=-2.8 required=4.2 tests=ALL_TRUSTED autolearn=failed version=3.0.2 X-Spam-Checker-Version: SpamAssassin 3.0.2 (2004-11-16) on server.baldwin.cx cc: Doug White cc: cvs-src@FreeBSD.org cc: src-committers@FreeBSD.org cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/kern uipc_mbuf.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 03 Mar 2005 13:07:40 -0000 On Mar 3, 2005, at 1:24 AM, Alan Cox wrote: > On Thu, Mar 03, 2005 at 02:41:37AM +0000, Doug White wrote: >> dwhite 2005-03-03 02:41:37 UTC >> >> FreeBSD src repository >> >> Modified files: >> sys/kern uipc_mbuf.c >> Log: >> Insert volatile cast to discourage gcc from optimizing the read >> outside >> of the while loop. >> >> Suggested by: alc >> MFC after: 1 day >> >> Revision Changes Path >> 1.144 +4 -1 src/sys/kern/uipc_mbuf.c > > I tend to believe that the sparc64's casa() implementation is the real > culprit here. Specifically, I don't believe the right asm operand > constraints are being used. If I'm correct, the addition of volatile > here is unnecessary. Can we hold the MFC until this hypothesis is > proven or disproven? Yes, it looks like it isn't clobbering "memory" which atomic operations on other architectures do. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org