From owner-freebsd-hackers@FreeBSD.ORG Thu Sep 16 11:59:52 2010 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 6576F1065672 for ; Thu, 16 Sep 2010 11:59:52 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id 32C408FC1E for ; Thu, 16 Sep 2010 11:59:52 +0000 (UTC) Received: from bigwig.baldwin.cx (66.111.2.69.static.nyinternet.net [66.111.2.69]) by cyrus.watson.org (Postfix) with ESMTPSA id C17A246B8A; Thu, 16 Sep 2010 07:59:51 -0400 (EDT) Received: from jhbbsd.localnet (smtp.hudson-trading.com [209.249.190.9]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id 6EE038A03C; Thu, 16 Sep 2010 07:59:50 -0400 (EDT) From: John Baldwin To: cronfy Date: Thu, 16 Sep 2010 07:59:49 -0400 User-Agent: KMail/1.13.5 (FreeBSD/7.3-CBSD-20100819; KDE/4.4.5; amd64; ; ) References: <201009151509.49728.jhb@freebsd.org> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201009160759.49179.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.0.1 (bigwig.baldwin.cx); Thu, 16 Sep 2010 07:59:50 -0400 (EDT) X-Virus-Scanned: clamav-milter 0.95.1 at bigwig.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-2.6 required=4.2 tests=AWL,BAYES_00 autolearn=ham version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on bigwig.baldwin.cx Cc: freebsd-hackers@freebsd.org Subject: Re: is vfs.lookup_shared unsafe in 7.3? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 16 Sep 2010 11:59:52 -0000 On Thursday, September 16, 2010 3:53:47 am cronfy wrote: > >> Hello, > >> > >> Trying to overtake high server load (sudden peaks of 15%us/85%sy, LA > > >> 40, very slow lstat() at these moments, looks like some kind of lock > >> contention) I enabled vfs.lookup_shared=1 on two servers today. One is > >> FreeBSD-7.3 kernel csup'ed and built Sep 9 2010 and other is > >> FreeBSD-7.3 csup'ed and built Jul 16 2010. > >> > >> The server with more fresh kernel is running nice and does not show > >> high load anymore. But on the second server it did not help. More, > >> after a few hours of work with vfs.lookup_shared=1 I noticed processes > >> stucked in "ufs" state. I tried to kill them with no luck. Disabling > >> vfs.lookup_shared freezed the whole system. > >> > >> So, is vfs.lookup_shared=1 unsafe in 7.3? Did it become more stable > >> between 16 Jul and 9 Sep (is it the reason why first system is still > >> running?), or should I expect that it will freeze in a near time too? > >> > >> Thanks in advance! > > > > No, 7.3 has a bug that can cause these hangs that is probably made worse by > > vfs.lookup_shared=1, but can occur even if it is disabled. You want > > these fixes applied (in order, one of them reverts part of another): > > Thank you for the fix and for the explanation, that's exactly what I > wanted to know. Just to be sure: do these patches completely fix the > bug with hangs (even without vfs.lookup_shared=1)? Yes. -- John Baldwin