Re: [PATCH 3 of 3] xen: sched_credit: add some tracing

[Dario Faggioli <raistlin@linux.it>]

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On Wed, 2012-12-05 at 12:01 +0000, Ian Campbell wrote: 
> > As I tried to explain in the comment, I just wanted to avoid checking
> > for !tb_init_done more than once, as this happens within a loop and, at
> > least potentially, there may be more CPUs to tickle (and thus more calls
> > to TRACE_1D).
> 
> If tb_init_done isn't marked volatile or anything like that isn't the
> check hoisted out of the loop by the compiler?
> 
Good point. As they're all macros, yes, I think that is something very
likely to happen... Although, I haven't checked the generated code, I'll
take a look. Thanks.

> > I take this comment of yours as you not thinking that is
> > something worthwhile, right? If so, I can definitely turn this into a
> > "standard" TRACE_1D() call.
> 
> Or maybe consider __TRACE_1D and friends which omit the check?
> 
Mmm... It may well be me, but my

$ grep __TRACE xen/* -R

does not show any results... What am I missing?

Dario

-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://retis.sssup.it/people/faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)



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