From owner-freebsd-current@FreeBSD.ORG Wed Apr 20 15:22:27 2005 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from green.homeunix.org (freefall.freebsd.org [216.136.204.21]) by hub.freebsd.org (Postfix) with ESMTP id 27EE916A4CE; Wed, 20 Apr 2005 15:22:27 +0000 (GMT) Received: from green.homeunix.org (green@localhost [127.0.0.1]) by green.homeunix.org (8.13.3/8.13.1) with ESMTP id j3KFKdre072379; Wed, 20 Apr 2005 11:20:39 -0400 (EDT) (envelope-from green@green.homeunix.org) Received: (from green@localhost) by green.homeunix.org (8.13.3/8.13.1/Submit) id j3KFKcc0072378; Wed, 20 Apr 2005 11:20:38 -0400 (EDT) (envelope-from green) Date: Wed, 20 Apr 2005 11:20:38 -0400 From: Brian Fundakowski Feldman To: Marc Olzheim Message-ID: <20050420152038.GI1157@green.homeunix.org> References: <20050418203321.GA88774@stack.nl> <20050419133227.GA11612@stack.nl> <20050419151800.GE1157@green.homeunix.org> <20050419160258.GA12287@stack.nl> <20050419160900.GB12287@stack.nl> <20050419161616.GF1157@green.homeunix.org> <20050419204723.GG1157@green.homeunix.org> <20050420140409.GA77731@stack.nl> <20050420142448.GH1157@green.homeunix.org> <20050420143842.GB77731@stack.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050420143842.GB77731@stack.nl> User-Agent: Mutt/1.5.6i cc: freebsd-hackers@freebsd.org cc: freebsd-current@freebsd.org Subject: Re: NFS client/buffer cache deadlock X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 20 Apr 2005 15:22:27 -0000 On Wed, Apr 20, 2005 at 04:38:42PM +0200, Marc Olzheim wrote: > On Wed, Apr 20, 2005 at 10:24:48AM -0400, Brian Fundakowski Feldman wrote: > > > It does and it seems to work. The NFS performance drops considerably > > > though, from 8/9 MByte/s to 3/4 on sequential reads for instance. > > > > > > kern/79208 is fixed by this indeed, in that I get short writes (in case > > > of my test server at 1802240+ bytes, so './writev 2 foo' fails... > > > > Performance drops in what cases? > > Hmm, seems only to happen in large sequential reads... It might just be > the FreeBSD 4.6 NFS server that is the problem though. I've had more NFS > troubles with it. Reads should be totally unaffected... > Btw.: I'm not sure write(),writev() and pwrite() are allowed to do short > writes on regular files... ? Our manpage is incorrect; POSIX states that they are (see earlier e-mail). There really is no alternative -- we simply can't build an NFS transaction larger than our buffer cache can accomodate. Note that short wries won't happen for normal buffer sizes, only excessively large ones. I really don't believe that writev() is meant to be used so that you can write gigantic data structures in a single transaction... -- Brian Fundakowski Feldman \'[ FreeBSD ]''''''''''\ <> green@FreeBSD.org \ The Power to Serve! \ Opinions expressed are my own. \,,,,,,,,,,,,,,,,,,,,,,\