Re: [PATCH 6/8] perf: Account freq events per cpu

[Frederic Weisbecker]

On Thu, Aug 01, 2013 at 04:06:15PM +0200, Peter Zijlstra wrote:
> On Thu, Aug 01, 2013 at 04:03:52PM +0200, Peter Zijlstra wrote:
> > On Thu, Aug 01, 2013 at 03:55:27PM +0200, Frederic Weisbecker wrote:
> > > On Thu, Aug 01, 2013 at 03:31:55PM +0200, Peter Zijlstra wrote:
> > > > 
> > > > Where the freq thing is new and shiney, but we already had the other
> > > > two. Of those, cgroup events must be per cpu so that should be good,
> > > > the branch_stack thing tests ATTACH_TASK, which should also be good, but
> > > > leaves me wonder wth they do for those that are attached to tasks.
> > > > 
> > > > But yes, the frequency thing is borken.
> > > 
> > > Aie, so the freq thing,  I can either account to all CPUs (inc to all
> > > and send an IPI to all), or when the event scheds in/out. Probably we
> > > should do the former to avoid sending an IPI at all context switches.
> > 
> > Yeah, just go with a single global state for now..
> 
> The perf default is to create inherited counter, which are per cpu
> anyway. So we'll not loose much.

So you mean that I keep the per cpu state when event->cpu != -1 and also have
a global counter for the others. Right?
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