Re: [Xen-devel] [PATCH RFC] xen: if on Xen, "flatten" the scheduling domain hierarchy

From: Dario Faggioli
Date: Tue Sep 15 2015 - 10:32:41 EST

On Thu, 2015-08-27 at 11:24 +0100, George Dunlap wrote:
> On 08/18/2015 04:55 PM, Dario Faggioli wrote:

> > *** Intel(R) Xeon(R) X5650 @ 2.67GHz
> > *** pCPUs 48 DOM0 vCPUS 16
> > *** RAM 393138 MB DOM0 Memory 9955 MB
> > *** NUMA nodes 2
> > =======================================================================================================================================
> > MAKE XEN (lower == better)
> > =======================================================================================================================================
> > # of build jobs -j1 -j20 -j24 -j48** -j62
> > vanilla/patched vanilla patched vanilla patched vanilla patched vanilla patched vanilla patched
> > ---------------------------------------------------------------------------------------------------------------------------------------
> > 267.78 233.25 36.53 35.53 35.98 34.99 33.46 32.13 33.57 32.54
> > 268.42 233.92 36.82 35.56 36.12 35.2 34.24 32.24 33.64 32.56
> > 268.85 234.39 36.92 35.75 36.15 35.35 34.48 32.86 33.67 32.74
> > 268.98 235.11 36.96 36.01 36.25 35.46 34.73 32.89 33.97 32.83
> > 269.03 236.48 37.04 36.16 36.45 35.63 34.77 32.97 34.12 33.01
> > 269.54 237.05 40.33 36.59 36.57 36.15 34.97 33.09 34.18 33.52
> > 269.99 238.24 40.45 36.78 36.58 36.22 34.99 33.69 34.28 33.63
> > 270.11 238.48 41.13 39.98 40.22 36.24 38 33.92 34.35 33.87
> > 270.96 239.07 41.66 40.81 40.59 36.35 38.99 34.19 34.49 37.24
> > 271.84 240.89 42.07 41.24 40.63 40.06 39.07 36.04 34.69 37.59
> > ---------------------------------------------------------------------------------------------------------------------------------------
> > Avg. 269.55 236.688 38.991 37.441 37.554 36.165 35.77 33.402 34.096 33.953
> > ---------------------------------------------------------------------------------------------------------------------------------------
> > Std. Dev. 1.213 2.503 2.312 2.288 2.031 1.452 2.079 1.142 0.379 1.882
> > ---------------------------------------------------------------------------------------------------------------------------------------
> > % improvement 12.191 3.975 3.699 6.620 0.419
> > ========================================================================================================================================
>
> I'm a bit confused here as to why, if dom0 has 16 vcpus in all of your
> tests, you change the -j number (apparently) based on the number of
> pcpus available to Xen. Wouldn't it make more sense to stick with
> 1/6/8/16/24? That would allow us to have actually comparable numbers.
>
Bah, no, sorry, that was a mistake I made when I cut-&-past'ed the
tables in the email... Dom0 always have as much vCPUs as the host has
pCPUs. I know this is a rather critical piece of information, so sorry
for messing it up! :-/

> But in any case, it seems to me that the numbers do show a uniform
> improvement and no regressions -- I think this approach looks really
> good, particularly as it is so small and well-contained.
>
Yeah, that seems the case... But I really would like to try more
configurations and more workloads. I'll do that ASAP.

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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