Re: [patch] Performance Counters for Linux, v2

[Ingo Molnar <mingo@elte.hu>]

* Chris Friesen <cfriesen@nortel.com> wrote:

> Ingo Molnar wrote:
>
>> When there are two (or more) hw metrics to profile, the ideally best 
>> (i.e. the statistically most stable and most relevant) sampling for 
>> the two statistical variables (say of l2_misses versus l2_accesses) is 
>> to sample them independently, via their own metric. Not via a static 
>> 1khz rate - or via picking one of the variables to generate samples.
>
> Regardless of sampling method, don't you still want some way to 
> enable/disable the various counters as close to simultaneously as 
> possible?

If it's about counter control for the monitored task, then we sure could 
do something about that. (apps/libraries could thus select a subset of 
functions to profile/measure, runtime, etc.)

If it's about counter control for the profiler/debugger, i'm not sure how 
useful that is - do you have a good usecase for it?

	Ingo