Re: [PATCH 1/3] perf: add context field to perf_event

[Will Deacon]

On Tue, Jul 12, 2011 at 10:36:05AM +0100, Avi Kivity wrote:
> On 07/12/2011 12:31 PM, Peter Zijlstra wrote:
> > >
> > >  But it means that 'current' is not set to the right value.  If the
> > >  function depends on it, then it will misbehave.  And in fact
> > >  preempt_notifier_register(), which is the function we want to call here,
> > >  does depend on current.
> > >
> > >  Of course we need to find more users for this, but I have a feeling this
> > >  will be generally useful.  The alternative is to keep adding bits to
> > >  thread_info::flags.
> >
> > Using TIF_bits sounds like a much better solution for this, wakeups are
> > really rather expensive and its best to avoid extra if at all possible.
> >
> 
> We do need a way to make the task look at them.

... especially without pushing this down into the arch code where I don't
think it belongs.
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