Messages in this thread | | | Date | Thu, 26 Jan 2012 12:26:36 +0100 | From | Jens Axboe <> | Subject | Re: [RFC PATCH v1 1/2] sched: unified sched_powersavings sysfs tunable |
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On 01/26/2012 12:08 PM, Peter Zijlstra wrote: > 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.
Yeah, I think that would suit my purpose nicely, in fact. What level of cache sharing is being used here? The block code wanted a per-socket type operation, but since it's a heuristic, perhaps the above is even better (or equivelant, perhaps).
-- Jens Axboe
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