From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: smiler <xlinghust@gmail.com>
Cc: xen-devel@lists.xensource.com
Subject: Re: a strange issue on disk scheduler in xen
Date: Fri, 15 Mar 2013 09:23:59 -0400 [thread overview]
Message-ID: <20130315132358.GJ8582@phenom.dumpdata.com> (raw)
In-Reply-To: <1363243207173-5714815.post@n5.nabble.com>
On Wed, Mar 13, 2013 at 11:40:07PM -0700, smiler wrote:
> Hi all,
>
> In Xen 4.0 with Linux 2.6.18.8, noop is default scheduler in dom U. In Xen
> 4.0 with Linux 2.6.31.8, CFQ is default scheduler in domU. In the both
> setup, CFQ is default scheduler in dom0. I compare the execution time of two
> seqenatil read applications run on a domU under noop of domU with under cfq
> of domU in both two Linux kernel.
> The sequential read application is generated by sysbench to read 1gb, like
> that: sysbench --num-threads=16 --test=fileio --file-total-size=1G
> --file-test-mode=seqrd prepare/run/cleanup
>
> I find a strange phenomenon as following:
> in Xen 4.0 with Linux 2.6.18.8
> noop in domU
> seqrd 1: 34.90s seqrd2: 32.49s
> cfq in domU
> seqrd 1: 245.94s seqrd2: 256.09s
> In this situation, the execution time of seqrd under CFQ of domU is much
> worse than that under noop of domU.
> However, in Xen 4.0 with Linux 2.6.31.8:
> noop in domU
> seqrd1: 36.83s seqrd 2: 37.01s
> CFQ in domU
> seqrd1: 35.68s seqrd 2: 35.76s
> In this situation, the execution time of seqrd under CFQ of domU is almost
> same as under noop of domU.
>
> The comparsion between noop and cfq of domU in Xen 4.0 with Linux 2.6.18 is
> so different from that in Xen 4.0 with Linux 2.6.31.8, It is very very
> strange. I also do the experiment in differnt machines, the results are
> same. So does anyone know the reason?
You are using ancient code. It might be very well that there were bugs in 2.6.18.
>
>
>
> --
> View this message in context: http://xen.1045712.n5.nabble.com/a-strange-issue-on-disk-scheduler-in-xen-tp5714815.html
> Sent from the Xen - Dev mailing list archive at Nabble.com.
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
>
next prev parent reply other threads:[~2013-03-15 13:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-14 6:40 a strange issue on disk scheduler in xen smiler
2013-03-15 13:23 ` Konrad Rzeszutek Wilk [this message]
2013-03-15 13:40 ` Ian Campbell
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