>On Mon, Mar 29, 1999 at 01:56:40PM +0200, Andrea Arcangeli wrote:
>> About the volatile thing the reason I thought it's not needed is that we
>> care that rdtsc is run always at the same offset of code. We care only
>> about the _delta_ between the two rdtsc. So basically I seen not using
>> __volatile__ as a feature. Comments?
>
> asm("rdtsc %0" : "=A"(start));
> something;
> asm("rdtsc %0" : "=A"(stop));
I explained myself very badly. My delta could be intended as the delta you
show above.
My delta instead is the time between _two_ schedule.
schedule()
{
something
real-rdtsc
something
}
The important thing is that real-rdtsc is always run at the same offset
(and this is implicit enforced in the asm compilation).
schedule()
{
real-rdtsc
something
something
}
This order would work fine too.
schedule()
{
something
something
real-rdtsc
}
This order would be fine too.
Do you see my point now?
So there's no bug, but you are asking for a semantical change of
get_cycles().
Andrea Arcangeli
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