Re: [RFC PATCH v1 1/2] sched: unified sched_powersavings sysfstunable

[Peter Zijlstra]

On Thu, 2012-01-26 at 11:42 +0100, Jens Axboe wrote:
> On 01/25/2012 03:53 PM, Peter Zijlstra wrote:

> > Jens, what is this thing trying to do?
> 
>The intent of the code
> is to return the first CPU in the "group" that the passed in core/thread
> belongs to. This is used to decide whether to perform a completion
> locally, or to send it off to a different "group".

Would you perhaps have meant to identify some shared cache domain?

In the scheduler core code we have (for CONFIG_SMP):

  static int ttwu_share_cache(int this_cpu, int that_cpu);

which returns true if this and that share a cache and false otherwise.
Would that suffice or do you need a slightly different form? That is, we
should provide you with some API and avoid you having to poke around
with CONFIG_SCHED* and topology bits methinks.

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