On Fri, Jul 27, 2012 at 01:56:36PM +0200, Frederic Weisbecker wrote:

SNIP

> 
> The problem is more general than that I think.
> We need to be able to define finer grained contexts than just
> "task" and/or "CPU".
> 
> And reusing events themselves would be a nice interface.
> 
> For example create 3 events:
> 
> A = irq entry tracepoint
> B = irq exit tracepoint
> C = cpu-cycles
> 
> And say: I want to count cpu-cycles when event A fires and stop counting
> when B fires.
> 
> With that you can count cpu cycles on irqs.
> 
> You could use any event you want to define your contexts: lock, functions, 
> etc...
> 
> And even uprobes to define areas in userspace to profile. Would that solve
> the initial problem in the thread? Like hook on function library entry/exit?
> 
> I talked about that to Jiri Olsa several times. May be he would be interested
> in implementing this. I posted some patchets one year ago but got sidetracked.
> 
> This can give you an idea from where we can start: 
> https://lkml.org/lkml/2011/3/14/346
> 
> Jiri, would you be interested in working on this?

yep, I remember also talking about A/B being functions entry/exit

I think that was also the initial push for having ftrace perf events
support, which already got in.

I'll check ;)

jirka
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