Alan Cox wrote:
>
> > First blush is HELL YES! The issue is accounting. When you
> > ask how long a program ran, you are looking at the
> > accounting that happens on a tick. This is where one of two
>
> Thats also an implementation issue. Note that the current code is also
> wildly inaccurate. Mr Shannon says we are good to at best 50 run/sleep
> changes a second. I've got "100% busy" workloads that are 99% asleep.
>
> Tracking cpu usage at task switch works a lot better for newer processors
> which as well as having rdtsc also have performance counters. In fact you
> can do much more interesting things on modern PC class platforms like
> scheduling using pre-emption interrupts based on instructions executed,
> memory accesses and more.
>
Oh, I agree. Hardware could make all this a lot easier.
-- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Real time sched: http://sourceforge.net/projects/rtsched/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Mon Jul 15 2002 - 22:00:21 EST