From owner-cvs-all@FreeBSD.ORG Wed Aug 4 21:40:59 2004 Return-Path: Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 1D14616A4CE; Wed, 4 Aug 2004 21:40:59 +0000 (GMT) Received: from cs.rice.edu (cs.rice.edu [128.42.1.30]) by mx1.FreeBSD.org (Postfix) with ESMTP id C17AF43D2F; Wed, 4 Aug 2004 21:40:58 +0000 (GMT) (envelope-from alc@cs.rice.edu) Received: from localhost (calypso.cs.rice.edu [128.42.1.127]) by cs.rice.edu (Postfix) with ESMTP id 60D604AB09; Wed, 4 Aug 2004 16:40:58 -0500 (CDT) Received: from cs.rice.edu ([128.42.1.30]) by localhost (calypso.cs.rice.edu [128.42.1.127]) (amavisd-new, port 10024) with LMTP id 06519-01-66; Wed, 4 Aug 2004 16:40:58 -0500 (CDT) Received: by cs.rice.edu (Postfix, from userid 19572) id 045E04AA94; Wed, 4 Aug 2004 16:40:58 -0500 (CDT) Date: Wed, 4 Aug 2004 16:40:57 -0500 From: Alan Cox To: Brian Fundakowski Feldman Message-ID: <20040804214057.GC10853@cs.rice.edu> References: <200408042031.i74KVKUf039025@repoman.freebsd.org> <200408041634.03998.jhb@FreeBSD.org> <20040804213236.GA58239@green.homeunix.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040804213236.GA58239@green.homeunix.org> User-Agent: Mutt/1.4.2i X-Virus-Scanned: by amavis-20030616-p7 at cs.rice.edu cc: cvs-src@FreeBSD.org cc: src-committers@FreeBSD.org cc: cvs-all@FreeBSD.org cc: John Baldwin Subject: Re: cvs commit: src/sys/i386/i386 pmap.c src/sys/kern subr_witness.c X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 04 Aug 2004 21:40:59 -0000 On Wed, Aug 04, 2004 at 05:32:36PM -0400, Brian Fundakowski Feldman wrote: > On Wed, Aug 04, 2004 at 04:34:03PM -0400, John Baldwin wrote: > > On Wednesday 04 August 2004 04:31 pm, John Baldwin wrote: > > > jhb 2004-08-04 20:31:19 UTC > > > > > > FreeBSD src repository > > > > > > Modified files: > > > sys/i386/i386 pmap.c > > > sys/kern subr_witness.c > > > Log: > > > Remove a potential deadlock on i386 SMP by changing the lazypmap ipi and > > > spin-wait code to use the same spin mutex (smp_tlb_mtx) as the TLB ipi > > > and spin-wait code snippets so that you can't get into the situation of > > > one CPU doing a TLB shootdown to another CPU that is doing a lazy pmap > > > shootdown each of which are waiting on each other. With this change, > > > only one of the CPUs would do an IPI and spin-wait at a time. > > > > Both this patch and the previous I have tested locally and also sent out to > > current@ for testing. However, I received zero feedback (not even useless > > feedback), so they may theoretically be risky. > > "No feedback is good feedback" -- those changes have caused no problems > for me during non-PREEMPTION-only testing on my dual Athlon. > Peter's recent changes to where and when we call pmap_release() signal the intention to eliminate this code. Alan