Re: Unified tracing buffer

[Mathieu Desnoyers]

* Darren Hart (darren@xxxxxxxxxx) wrote:
> On Mon, Sep 22, 2008 at 7:02 PM, Mathieu Desnoyers <compudj@xxxxxxxxxxxxxxxxxx>
> > So only in the specific case of instrumentation of things like locking,
> > where it is possible to insure that instrumentation is synchronized with
> > the instrumented operation, does it make a difference to choose the TSC
> > (which implies a slight delta between the TSCs due to cache line delays
> > at synchronization and delay due to TSCs drifts caused by temperature)
> > over an atomic increment.
> >
> 
> Hrm, i think that overlooks the other reason to use a time based counter over
> an atomic increment: you might care about time.  Perhaps one might be less
> concerned with actual order tightly grouped events and more concerned with the
> actual time delta between more temporally distant events.  In that case, using
> a clocksource would still be valuable. Although admitedtly the caller could
> embed that in their payload, but since we seem to agree we need some kind of
> counter, the time-based counter appears to be the most flexible.
> 
> Thanks,
> 

See my answer to Linus for a proposal on how to do both :)

Mathieu

> -- 
> Darren Hart
> 

-- 
Mathieu Desnoyers
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