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

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

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).

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
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)

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