[ltt-dev] LTTV Enhancement (integrated in lttv 0.12.24)

Mathieu Desnoyers mathieu.desnoyers at polymtl.ca
Fri Nov 27 12:42:25 EST 2009


LTTV 0.12.24 integrate the support for try_wakeup and "wait for cpu".
Thanks !

Mathieu


* Mathieu Desnoyers (mathieu.desnoyers at polymtl.ca) wrote:
> * Pierre-Marc Fournier (pierre-marc.fournier at polymtl.ca) wrote:
> > Mathieu Desnoyers wrote:
> > > * Chris Smowton (cs448 at cam.ac.uk) wrote:
> > >> Hey,
> > >>
> > >> Here's a slightly more constructive patch: this one adds support in
> > >> LTTV's generic state monitoring code and its control flow visualiser to
> > >> note when a process is woken by another process using the
> > >> sched_try_wakeup event.
> > >>
> > >> Previously the woken process would continue to register its old state
> > >> until such time as it got scheduled; here the process transitions to
> > >> WAIT_CPU state (like preempted processes, indicating it is ready to run
> > >> but not currently scheduled). Ordinarily we see this state exist very
> > >> briefly, in between the device driver IRQ (typically) clearing it to run
> > >> and the scheduler invocation after irq_exit, but on a heavily loaded
> > >> system we might see a large stripe of dark yellow indicating the process
> > >> is ready but cannot yet be allocated a core.
> > >>
> > > 
> > > This is indeed the right thing to do ! :) Thanks very much for the
> > > patch.
> > > 
> > > I'll wait for feedback from Pierre-Marc, who maintains the resource
> > > view, to see if this view too need to be updated. When I get his OK,
> > > I'll pull your patch.
> > > 
> > 
> > This looks like an excellent idea. You have my OK.
> > 
> > pmf
> 
> Yep, I looked at it, and it seems good. I did a bit of coding-style
> modification to the new sched_try_wakeup() function and merged the
> patch.
> 
> I think we should probably also deal with the sched wakeup_new_task
> event, shouldn't we ? (a patch to support this would be welcome)
> 
> Thanks,
> 
> Mathieu
> 
> -- 
> Mathieu Desnoyers
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> 
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-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68




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