Re: [RFC PATCH 3/3] idle: store the idle state index in the struct rq

[Arjan van de Ven]

On 2/11/2014 8:41 AM, Peter Zijlstra wrote:
> On Mon, Feb 03, 2014 at 08:17:47AM -0800, Arjan van de Ven wrote:
> > On 2/3/2014 6:56 AM, Peter Zijlstra wrote:
> > if there's a simple api like
> >
> > sched_cpu_cache_wiped(int llc)
> >
> > that would be very nice for this; the menuidle side knows this
> > for some cases and thus can just call it. This would be a very
> > small and minimal change
> >
> > * if you don't care about llc vs core local caches then that
> >    parameter can go away
> >
> > * I assume this is also called for the local cpu... if not then we
> >    need to add a cpu number argument
> >
> > * we can also call this from architecture code when wbinvd or the
> >    arm equivalent is called etc
>
> A little something like so?

is there value also in doing a cpu level cache flush?
(cpu cache flush we know from the C state, for the llc cache flush we need to read an MSR
on x86. Not insane expensive but not zero either)


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