On Tue, 26 Jun 2007 10:38:13 +0200 Ingo Molnar <[email protected]> wrote:
>
> > - __exit_signal() does apparently-unlocked 64-bit arith. Is there
> > some implicit locking here or do we not care about the occasional
> > race-induced inaccuracy?
>
> do you mean the tsk->se.sum_exec_runtime addition, etc? That runs with
> interrupts disabled so sum_sched_runtime is protected.
>
> > (ditto, lots of places, I expect)
>
> which places do you mean?
I forget ;) There seemed to be rather a lot of 64-bit addition with no
obvious locking in sight, that's all.
> > ...
> > (Gee, there's shitloads of 64-bit stuff in there. Does it all
> > _really_ need to be 64-bit on 32-bit?)
>
> yes - CFS is fundamentally designed for 64-bit, with still pretty OK
> arithmetics performance for 32-bit.
It may have been designed for 64-bit, but was that the correct design? The
cost on 32-bit appears to be pretty high. Perhaps a round of uninlining
will help.
> > - overall, CFS takes sched.o from 41157 of .text up to 48781 on x86_64,
> > which at 18% is rather a large bloat. Hopefully a lot of this is
> > the new debug stuff.
>
> > - On i386 sched.o went from 33755 up to 43660 which is 29% growth.
> > Possibly acceptable, but why did it increase a lot more than the x86_64
> > version? All that 64-bit arith, I assume?
>
> the main reason is the sched debugging stuff:
That would serve to explain the 18% growth on x86_64. But why did i386
grow by much more: 29%? I'd be suspecting all the new 64-bit arithmetic.
-
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