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Re: high load and xfsaild in d

To: linux-xfs@xxxxxxxxxxx
Subject: Re: high load and xfsaild in d
From: Keith Keller <kkeller@xxxxxxxxxxxxxxxxxxxxxxxxxx>
Date: Thu, 22 Nov 2012 20:34:06 -0800
References: <sn23o9xkh3.ln2@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> <20121123025624.GC32450@dastard>
User-agent: slrn/0.9.9p1 (Linux)
On 2012-11-23, Dave Chinner <david@xxxxxxxxxxxxx> wrote:
> That's a side effect of a minimal set of bug fixes that were needed
> to avoid a load related log space hang. Those fixes disabled the
> aild idling logic so the aild acts as a watchdog, so they wake up
> every 50ms to check if there's anything to do. You'll find that
> 3.0.x stable kernels have the same behaviour.
>
> The aild idling logic was re-enabled in mainstream kernels after the
> root cause of the log space hangs was diagnosed and fixed, but I
> can't see it ever being re-enabled in a CentOS 6.3 kernel....

Thanks for the clarification, Dave.  It sounds like I would need to
either wait for this fix to hit the CentOS release kernel, or compile my
own.  Is this likely to be an actual problem short-term, or should it
safe to put off any fixes for a few weeks?  If it's a potential problem
beyond just impacting the system load, I'd want to try to fix it sooner.

Do you know why I might not see this behavior on a different CentOS 6.x
kernel?

Linux xxxxxx 2.6.32-279.5.2.el6.x86_64 #1 SMP Fri Aug 24 01:07:11 UTC 2012 
x86_64 x86_64 x86_64 GNU/Linux

This kernel has its one aild thread in state S.  Is the bug state an
issue if there's more than one XFS filesystem mounted?  Aside from nfsd
and smbd (and the storage backend), that's the only obvious difference
I can find between the two boxes.  Seems unlikely, but IIRC the original
bug was a very rare case.

--keith

-- 
kkeller@xxxxxxxxxxxxxxxxxxxxxxxxxx


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