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From Wayne <wav...@gmail.com>
Subject Re: pdflush 100% cpu
Date Thu, 19 Jan 2012 19:53:49 GMT
It was the kernel...thanks for the help. We had considered but could not
really believe a slight kernel version difference would cause this.

Thanks

On Wed, Jan 18, 2012 at 11:47 PM, Stack <stack@duboce.net> wrote:

> On Wed, Jan 18, 2012 at 8:40 AM, Wayne <wav100@gmail.com> wrote:
> > We have set up a new cluster and are now seeing pdflush processes pegged
> at
> > 100% cpu during compaction. Is this normal? It sometimes "looks" like
> > pdflush is pegged at 100% for quite a while and the java cpu usage goes
> > down as if it is waiting on it to finish. We are using 0.90.4 on centos
> 5.5
> > with no swap. Is this a linux kernal issue due to no swap? This cluster
> is
> > the first time we have ever seen this but we are running a slightly newer
> > kernal than other cluster where we did not see this.
> >
>
> I've not noticed it Wayne (can't say I was particularly on the lookout
> for it but I suppose I'd have seen a 100%pdflush if it was going on).
>
> > Any ideas? Should we be worried about this? Is/can pdflush really be a
> > bottleneck to disk writes?
> >
>
> Could you try older kernel on one of the cluster members and see if it
> still 100%s?
>
> What about the pdflush tunings on the two clusters?  Are they the
> same?  (I was looking at this page:
> http://www.westnet.com/~gsmith/content/linux-pdflush.htm)
>
> St.Ack
>

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