Re: [Vserver] vsched and multi-CPU

From: Herbert Poetzl <herbert_at_13thfloor.at>
Date: Tue 30 May 2006 - 17:18:53 BST
Message-ID: <20060530161852.GC25265@MAIL.13thfloor.at>

On Tue, May 30, 2006 at 04:12:55PM +0200, Mehdi Bennani wrote:
> Hello,
>
> I've read the pages about vsched on
>
> http://linux-vserver.org/vsched+explained:
> http://linux-vserver.org/Scheduler+Parameters
>
> I'm trying to figure out how vserver deals with multi-processor
> systems and systems with hyperthreaded processors (detected as
> bi-processor).
>
> and I would like an explanation about something that seems ambigous
> to me:
>
> --Both pages seem to say that (fill-rate) / (interval) is the
> proportion for ONE processor in the system. But a sentence in
> http://linux-vserver.org/vsched+explained...:
>
> "So, if you have four CPUs and you want one context to get an average
> of one whole CPU to itself, then you'd set fill-rate to 1 and interval
> to 4."
>
> ... is not clear... does it mean that (fill-rate) / (interval) is the
> proportion for the FOUR CPU's?
>
> Where is the truth?

as usually the truth is somewhere inbetween ...
actually we have to differentiate here between
the stable and the devel releases, because:

stable has a single token bucket for all cpus
and the scheduler adds 'rate' tokens per cpu
and 'interval'

development has one token bucket per cpu and
two rate/interval values for each of them, to
control normal and idle time

> --Is a processor with Hyperthreading counted as two processors
> by vserver?

yes, as SMT appears quite similar to SMP at
least regarding the scheduler and runqueues

HTH,
Herbert

> Thanks,
>
> Mehdi Bennani
> _______________________________________________
> Vserver mailing list
> Vserver@list.linux-vserver.org
> http://list.linux-vserver.org/mailman/listinfo/vserver
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Received on Tue May 30 18:19:49 2006

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