Re: [RFC] [Patch 7/8] statistics infrastructure - exploitation prerequisite

From: Peter Chubb
Date: Tue May 16 2006 - 21:44:01 EST

>>>>> "Andi" == Andi Kleen <ak@xxxxxxx> writes:

Anrd> - do_gettimeofday potentially slow, reliable TOD clock,
Anrd> microsecond resolution
>> Slow, not necessarily safe to call in IRQ context.

Andi> It's only slow if the platform can't do better. On good hardware
Andi> it is fast. And yes it is safe to call in IRQ
Andi> context. Networking does that all the time.

Thanks for the clarification.

I measured do_gettimeofday on IA64 at around 120 cycles (mind you that
was some time ago now, before the last lot of time function revisions
in the kernel). Whether that's slow or not depends on your application.

Dr Peter Chubb peterc AT ERTOS within National ICT Australia
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