From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rob Ross <rross@mcs.anl.gov>
Subject: Re: readdirplus() as possible POSIX I/O API
Date: Tue, 05 Dec 2006 16:48:30 -0600
Message-ID: <4575F73E.6000800@mcs.anl.gov>
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Cc: Trond Myklebust <trond.myklebust@fys.uio.no>,
	Sage Weil <sage@newdream.net>,
	Christoph Hellwig <hch@infradead.org>,
	Brad Boyer <flar@allandria.com>,
	Anton Altaparmakov <aia21@cam.ac.uk>,
	Gary Grider <ggrider@lanl.gov>, linux-fsdevel@vger.kernel.org
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To: Latchesar Ionkov <lionkov@lanl.gov>
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Hi Lucho,

Andreas is right on mark. The problem here is that when one user kicks 
off an ls -l or ls -R on a cluster file system *while other users are 
trying to get work done*, all those stat RPCs and lock reclamations can 
kill performance.

We're not interested in a "ls -lR" top 500, we're interested in making 
systems more usable, more tolerant to everyday user behaviors.

Regards,

Rob

Latchesar Ionkov wrote:
> On 12/5/06, Andreas Dilger <adilger@clusterfs.com> wrote:
>> The primary goal (IMHO) of this syscall is to allow the filesystem
>> (primarily distributed cluster filesystems, but HFS and NTFS developers
>> seem on board with this too) to avoid tens to thousands of stat RPCs in
>> very common ls -R, find, etc. kind of operations.
> 
> I don't think that ls -R and find are that common cases that they need
> introduction of new operations in order to made them faster. On the
> other hand may be they are often being used to do microbenchmarks. If
> you goal is to make these filesystems look faster on microbenchmarks,
> then probably you have the right solution. For normal use, especially
> on clusters, I don't see any advantage of doing that.
> 
> Thanks,
>    Lucho