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Re: heavy VM load due to revamped pagebuf locking?

To: "HABBINGA,ERIK (HP-Loveland,ex1)" <erik_habbinga@xxxxxx>
Subject: Re: heavy VM load due to revamped pagebuf locking?
From: Andi Kleen <ak@xxxxxxx>
Date: Thu, 4 Apr 2002 18:44:24 +0200
Cc: "'linux-xfs@xxxxxxxxxxx'" <linux-xfs@xxxxxxxxxxx>
In-reply-to: <F341E03C8ED6D311805E00902761278C0C35DE3E@xfc04.fc.hp.com>; from erik_habbinga@hp.com on Thu, Apr 04, 2002 at 11:13:39AM -0500
References: <F341E03C8ED6D311805E00902761278C0C35DE3E@xfc04.fc.hp.com>
Sender: owner-linux-xfs@xxxxxxxxxxx
User-agent: Mutt/1.2.5i
On Thu, Apr 04, 2002 at 11:13:39AM -0500, HABBINGA,ERIK (HP-Loveland,ex1) wrote:
> I've updated to 2.4.18 w/ a XFS CVS download from 03/29/2002.  During SPEC
> testing, the VM takes over all CPU load as pagebuf_iostart starts waiting
> for memory, and then kmalloc starts waiting for memory.  All of this time
> spent in shrink_cache causes the SPEC test to time out.  Once the test
> stops, the box settles down and VM CPU load goes away.    All of the
> shrink_cache functions are waiting for schedule() to come back, because of
> the test for current->need_resched at the top of the shrink_cache loop.  For
> grins, I commented out that test, and now many nfsd processes are sitting in
> _pagebuf_find_lockable_buffer->pagebuf_iostart's call to pagebuf_iowait.
> Could the revamped pagebuf locking cause this behaviour?

You could test ist. Just revert that TAKE and test again.

-Andi

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