linux-kernel - Re: [2.6.34-rc2 NFS4 oops] open error path failure...

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Message-ID: <4BB35A53.5000003@oracle.com>
Date:	Wed, 31 Mar 2010 10:21:07 -0400
From:	Chuck Lever <chuck.lever@...cle.com>
To:	Daniel J Blueman <daniel.blueman@...il.com>
CC:	Trond Myklebust <trond.myklebust@....uio.no>,
	Al Viro <viro@...iv.linux.org.uk>, linux-nfs@...r.kernel.org,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [2.6.34-rc2 NFS4 oops] open error path failure...

On 03/31/2010 07:20 AM, Daniel J Blueman wrote:
> Talking of expensive, I see latencytop show>16000ms latency for
> writing pages when I have a workload that does large buffered I/O to
> an otherwise uncongested server. The gigabit network is saturated, and
> reads often stall for 1000-4000ms (!). Client has the default 16 TCP
> request slots, and server has 8 nfsds - the server is far from disk or
> processor-saturated. I'll see if there is any useful debugging I can
> get about this.

That latency is pretty much guaranteed to be due to a long RPC backlog 
queue on the client.  Bumping the size of the slot table to 128 and 
increasing the number of NFSD threads may help.

-- 
chuck[dot]lever[at]oracle[dot]com
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