Date: Wed, 4 Aug 2004 16:40:57 -0500 From: Alan Cox <alc@cs.rice.edu> To: Brian Fundakowski Feldman <green@FreeBSD.org> Cc: John Baldwin <jhb@FreeBSD.org> Subject: Re: cvs commit: src/sys/i386/i386 pmap.c src/sys/kern subr_witness.c Message-ID: <20040804214057.GC10853@cs.rice.edu> In-Reply-To: <20040804213236.GA58239@green.homeunix.org> References: <200408042031.i74KVKUf039025@repoman.freebsd.org> <200408041634.03998.jhb@FreeBSD.org> <20040804213236.GA58239@green.homeunix.org>
next in thread | previous in thread | raw e-mail | index | archive | help
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
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20040804214057.GC10853>