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Re: [Xen-devel] [PATCH OSSTEST] ts-debian-install: increase time allowed for xen-create-image

On Fri, 2016-01-15 at 15:44 +0100, Dario Faggioli wrote:
> On Fri, 2016-01-15 at 13:35 +0000, Ian Campbell wrote:
> > This step is consistently timing out when run on cubietruck-*.
> > Judging
> > from the logs it appears to be completing during the 30s slack added
> > by tcmdex (i.e. after the timeout message the rest of the output
> > appears in the test step log).
> > 
> > Looking at the results on arndale-* (which looks to pass reasonably
> > reliably) I see that the regular test-armhf-armhf-xl job takes around
> > 550s to do the xen-create-image while test-armhf-armhf-xl-rtds
> > typically takes around 1100s (twice as long).
> > 
> > On cubietruck-braque test-armhf-armhf-xl uses 900s. One could
> > therefore extrapolate that test-armhf-armhf-xl-rtds might need more
> > than 1800s and not be too surprised that it appears to need something
> > a bit more than 2000s in practice. 2500s seems like sufficient
> > headroom.
> > 
> > For comparisson with arm on x86 godello takes around 210s in the
> > normal case and 680s with RTDS (>3x slower) while nocera takes 265s
> > and 640s (2.4x). (Those are from nearby but not identical flights in
> > order to match up the host).
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > 
> Reviewed-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
> > ---
> > Dario, Meng, I suppose a 2-3x slow down with RTDS on a dom0 operation
> > (with no domains running) such as xen-create-image is not unexpected?
> > 
> Yes, as of now, I think it is. RTDS' default scheduling parameters
> throttle domains' vcpus to max 40% of CPU, non work conserving mode
> (i.e.m, they only consume up to that much even if there is idle time).

Thanks. 40% seems to correlate to the 2-3x slowdown we are seeing.
> I think this will have to change at some point, but for now, slowdowns
> for operation like the ones in xen-create-image are to be expected, and
> this patch looks therefore ok to me.
> Thanks and Regards,
> Dario

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