From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ragnar =?iso-8859-15?Q?Kj=F8rstad?= Subject: Re: NFSv4/pNFS possible POSIX I/O API standards Date: Wed, 6 Dec 2006 13:22:51 +0100 Message-ID: <20061206122251.GG17226@vestdata.no> References: <1164984094.5761.86.camel@lade.trondhjem.org> <20061203015203.GA5656@schatzie.adilger.int> <20061204073200.GB5637@schatzie.adilger.int> <1165245336.711.176.camel@lade.trondhjem.org> <4574C48A.8030007@mcs.anl.gov> <1165298200.5776.26.camel@lade.trondhjem.org> <20061205100748.GC5871@infradead.org> <1165330516.5742.24.camel@lade.trondhjem.org> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Christoph Hellwig , Rob Ross , Andreas Dilger , Sage Weil , Brad Boyer , Anton Altaparmakov , Gary Grider , linux-fsdevel@vger.kernel.org Return-path: Received: from stine.vestdata.no ([217.149.127.10]:52322 "EHLO stine.vestdata.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760543AbWLFMX7 (ORCPT ); Wed, 6 Dec 2006 07:23:59 -0500 To: Trond Myklebust Content-Disposition: inline In-Reply-To: <1165330516.5742.24.camel@lade.trondhjem.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Tue, Dec 05, 2006 at 09:55:16AM -0500, Trond Myklebust wrote: > > The again statlite and > > readdirplus really are the most sane bits of these proposals as the= y > > fit nicely into the existing set of APIs. The filehandle idiocy on > > the other hand is way of into crackpipe land. >=20 > ... > =20 > a) networked filesystem specific. The mask stuff etc adds no > value whatsoever to actual "posix" filesystems. In fact it is > telling the kernel that it can violate posix semantics. I don't see what's network filesystem specific about it. Correct me if I'm wrong, but today ls -l on a local filesystem will first do readdir and then n stat calls. In the worst case scenario this will generate n+= 1 disk seeks. Local filesystems go through a lot of trouble to try to make the disk layout of the directory entries and the inodes optimal so that readahea= d and caching reduces the number of seeks. With readdirplus on the other hand, the filesystem would be able to sen= d all the requests to the block layer and it would be free to optimize through disk elevators and what not.=20 And this is not simply an "ls -l" optimization. Allthough I can no loge= r remember why, I think this is exactly what imap servers are doing when opening up big imap folders stored in maildir.=20 --=20 Ragnar Kj=F8rstad Software Engineer Scali - http://www.scali.com Scaling the Linux Datacenter - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html