From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Latchesar Ionkov" Subject: Re: Re: Re: NFSv4/pNFS possible POSIX I/O API standards Date: Tue, 5 Dec 2006 18:10:20 +0100 Message-ID: References: <6.2.3.4.2.20061127213243.04f786c0@cic-mail.lanl.gov> <20061129090450.GA16296@infradead.org> <20061129122313.GG14315@parisc-linux.org> <20061129123913.GA15994@infradead.org> <4570ACD1.7060800@mcs.anl.gov> <4574BF52.6090600@mcs.anl.gov> <20061205170109.GP3013@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from nf-out-0910.google.com ([64.233.182.190]:13634 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S968468AbWLERKW (ORCPT ); Tue, 5 Dec 2006 12:10:22 -0500 Received: by nf-out-0910.google.com with SMTP id o25so280185nfa for ; Tue, 05 Dec 2006 09:10:20 -0800 (PST) To: linux-fsdevel@vger.kernel.org In-Reply-To: Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org ---------- Forwarded message ---------- From: Latchesar Ionkov Date: Dec 5, 2006 6:09 PM Subject: Re: Re: Re: NFSv4/pNFS possible POSIX I/O API standards To: Matthew Wilcox On 12/5/06, Matthew Wilcox wrote: > On Tue, Dec 05, 2006 at 05:47:16PM +0100, Latchesar Ionkov wrote: > > I think that the main problem is that all these file systems resove a > > path name, one directory at a time bringing the server to its knees by > > the huge amount of requests. I would like to see what the performance > > is if you a) cache the last few hundred lookups on the server side, > > and b) modify VFS and the file systems to support multi-name lookups. > > Just assume for a moment that there is no any way to get these new > > operations in (which is probaly going to be true anyway :). What other > > solutions can you think of? :) > > How exactly would you want a multi-name lookup to work? Are you saying > that open("/usr/share/misc/pci.ids") should ask the server "Find usr, if > you find it, find share, if you find it, find misc, if you find it, find > pci.ids"? That would be potentially very wasteful; consider mount > points, symlinks and other such effects on the namespace. You could ask > the server to do a lot of work which you then discard ... and that's not > efficient. It could be wasteful, but it could (most likely) also be useful. Name resolution is not that expensive on either side of the network. The latency introduced by the single-name lookups is :) Thanks, Lucho