Re: AMD X2 unsynced TSC fix?

[Lee Revell]

On Sat, 2006-10-28 at 02:00 +0200, Luca Tettamanti wrote:
> 
> As you say you cannot use it to do timing unless you disable any power
> management on the CPU. Otherwise you can count the elapsed ticks but
> you cannot convert the number to anything meaningful.
> You may be able to emulate rdtsc for userspace but then again the
> whole point of using rdtsc is that it should be uber-fast... if rdtsc
> is emulated then you can just use gettimeofday (which is also
> optimized to be *very* fast). No? 

gettimeofday() cannot be fast if it has to use the ACPI PM timer.  It's
50% slower on my shiny new "AMD Athlon(tm)64 X2 Dual Core Processor
3800+" than on my 600Mhz Via C3, which in general is about a 10x slower
machine.  That's a massive regression.

Lee

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/