linux-kernel - Re: [PATCH 0/4] 2.6.21-rc7 NFS writes: fix a series of issues

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Date:	Wed, 18 Apr 2007 00:26:16 -0500
From:	florin@...ha.net (Florin Iucha)
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Trond Myklebust <Trond.Myklebust@...app.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Adrian Bunk <bunk@...sta.de>,
	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] 2.6.21-rc7 NFS writes: fix a series of issues

On Tue, Apr 17, 2007 at 10:14:02PM -0700, Linus Torvalds wrote:
> On Tue, 17 Apr 2007, Florin Iucha wrote:
> > 
> > Already did.  Traces from vanilla kernel at
> >    http://iucha.net/nfs/21-rc7/big-copy
> 
> Well, there's a pdflush in io_schedule_timeout/congestion_wait, and 
> there's a nfsv4-scv in svc_recv/nfs_callback_sv, and a lot of processes 
> either just in schedule_timeout or similar "normal" waiting (pollwait 
> etc).
> 
> [ The call traces could be prettier, but sadly, even if you enable frame 
>   pointers, the x86-64 kernel is too stupid to follow them. So you kind of 
>   just have to ignore the noise) ]
> 
> The triggering process looks like it might be that "cp", it is in the 
> __wait_on_bit/sync_page/wait_on_page_bit/wait_on_page_writeback_range/ 
> filemap_fdatawait.
> 
> Is this a trace from the "big copy" hang, or from a gnome splashscreen 
> hang? It *looks* like it's a big copy. Yes/no?

It *is* big copy.

I am monitoring the copy on the server, using "iostat 5".  It writes
for a while at a fairly constant pace (on ext3 *), then it drops to 0 in 5-10
seconds and stays there...  Once I left it for a couple of hours and
it did not pick up.

Regards,
florin

(*) XFS exhibited wild ups and downs in the transaction rate, and JFS
starts strong then loses steam and slowly settles to about half ext3's
rate.

-- 
Bruce Schneier expects the Spanish Inquisition.
      http://geekz.co.uk/schneierfacts/fact/163

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