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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2012-12-05 at 12:15 +0000, Dario Faggioli wrote:
> 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?

I meant to define + use those macros.

Ian.



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