Re: [ckrm-tech] Re: [Lse-tech] [PATCH] cpusets - big numa cpu and memory placement

Peter Williams
2004-10-02T23:29:46Z

Hubertus Franke wrote:
>
>
> Paul Jackson wrote:
>
>> Hubertus wrote:
>>
>>> Marc, cpusets lead to physical isolation.
>>
>>
>>
>> This is slightly too terse for my dense brain to grok.
>> Could you elaborate just a little, Hubertus? Thanks.
>>
>
> A minimal quote from your website :-)
>
> "CpuMemSets provides a new Linux kernel facility that enables system
> services and applications to specify on which CPUs they may be
> scheduled, and from which nodes they may allocate memory."
>
> Since I have addressed the cpu section it seems obvious that
> in order to ISOLATE different workloads, you associate them onto
> non-overlapping cpusets, thus technically they are physically isolated
> from each other on said chosen CPUs.
>
> Given that cpuset hierarchies translate into cpu-affinity masks,
> this desired isolation can result in lost cycles globally.

This argument if followed to its logical conclusion would advocate the
abolition of CPU affinity masks completely.

>
> I believe this to be orthogonal to share settings. To me both
> are extremely desirable features.
>
> I also pointed out that if you separate mechanism from API, it
> is possible to move the CPU set API under the CKRM framework.
> I have not thought about the memory aspect.
>
> -- Hubertus
>
>
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--
Peter Williams pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
-- Ambrose Bierce