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Date: Sun, 25 Nov 2012 23:01:34 +0000
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Subject: Re: Ubuntu4/5 (juno/janus) filesystem operations are slow in
 comparison with other Ubuntu1-3.
From: Keith W <keith.wall@gmail.com>
To: builds@apache.org
Content-Type: text/plain; charset=ISO-8859-1

Hello Builds,

Would someone by able to answer my query please?

Thanks in advance, Keith.

On 12 November 2012 09:09, Keith W <keith.wall@gmail.com> wrote:
> Hello Builds
>
> I'm investigating a regular test failure we (Qpid) see on one of our
> Jenkins jobs (Qpid-Java-Java-DBY-TestMatrix).  The job is a matrix
> that is tied to the ubuntu label.   I notice that the test failure (a
> timeout) seems to occur when ubuntu4 or 5 is chosen as a build slave.
> Tests that normally take a seconds or less extend to tens of seconds
> or worse and the job is caught by the build timeout plugin  and a
> failure results.
>
> I'm still investigating, but at the moment, the application logs are
> pointing to a very slow filesystem as a likely cause.  I also see
> similar results timing sync and dd commands from a jenkins job.
> Script fragment and results are below.
>
> It would be helpful to me to know the spec of juno and janus machines
> including their filesystem spec and config (eg. RAID)   (the details
> are absent from www.apache.org/dev/machines.html).   Are these true
> machines or guest VMs?  Are you aware of anything else that may cause
> slow filesystem performance?
>
> Kind regards, Keith Wall.
>
>
>
> Script:
>
> time sync
> sh -c 'dd if=/dev/zero of=ddfile bs=8k count=200000 && sync'
> time sync
>
> ubuntu5
>
> time sync (before)
> real    0m6.513s
> user    0m0.000s
> sys     0m0.584s
> 200000+0 records in
> 200000+0 records out
> 1638400000 bytes (1.6 GB) copied, 3.58202 s, 457 MB/s
> real    0m32.567s
> user    0m0.016s
> sys     0m4.116s
> time sync (after)
> real    0m1.378s
> user    0m0.000s
> sys     0m0.552s
>
> ubuntu3 (for comparison):
>
> time sync (before)
> real    0m0.491s
> user    0m0.000s
> sys     0m0.372s
>
> 1638400000 bytes (1.6 GB) copied, 1.25777 s, 1.3 GB/s
> real    0m4.696s
> user    0m0.012s
> sys     0m1.608s
>
> time sync (after)
> real    0m0.376s
> user    0m0.000s
> sys     0m0.364s