[haiku-commits] Re: r41847 - in haiku/branches/developer/bonefish/signals: headers/private/kernel src/system/kernel/scheduler
- From: "Ingo Weinhold" <ingo_weinhold@xxxxxx>
- To: haiku-commits@xxxxxxxxxxxxx
- Date: Tue, 31 May 2011 19:51:47 +0200
Axel Dörfler wrote:
> Ingo Weinhold <ingo_weinhold@xxxxxx> wrote:
> > On 2011-05-31 at 09:30:21 [+0200], Axel Dörfler <axeld@xxxxxxxxxxxxxxxx>
> > > wrote:
> I'm pretty sure that GCC2 also inlined static functions automatically
> with optimizations turned on.
Maybe with -O3 (which we don't use) or in different circumstances. At least
here I can see three non-inlined context_switch() functions in my gcc 2 built
release kernel.
> One additional feature of GCC4, however,
> is to be able to inline methods over the bounds of an object file IIRC.
You mean the linker inlines already compiled functions into others? I somewhat
doubt that. I believe LLVM does this kind of optimization, but not with actual
machine code.
> > > which might make a measurable
> > > difference,
> > The overhead for the call is relatively small compared to what is
> > done when
> > switching the thread and even smaller with respect to the whole
> > *_reschedule() function. So, unless you measure the *_reschedule()
> > itself, I
> > seriously doubt that there is a measurable difference.
>
> Which contradicts itself - if there is a measurable difference in
> *_reschedule(), there will also be one when the scope gets larger :-)
No, that isn't generally true. Measurements can only be done with a certain
accuracy. Say, the change makes *_reschedule() 1% slower and the function
itself eats 1% CPU time under heavy load, the total effect of the change would
be 0.01%. I'm pretty sure this is not practically measurable.
CU, Ingo
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