Messages in this thread | | | Subject | Re: CPU frequency shifting "problems" | Date | Sat, 29 Sep 2001 00:09:04 +0100 (BST) | From | Alan Cox <> |
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> > We do 5uS per transition 4 transitions per bit, 64bits. So thats 1.2mS > > or using the PM timer thats 0.25 seconds > > OK ya lost me...;-)
I got my maths wrong by a slight factor of 1000, ignore me - there is a reason I didnt do maths at university 8)
> Both Windows and FreeBSD-CURRENT use the PM timer for udelays. It is 3579545 > Hz. ~2.71 ticks per usec. Read the PM timer, add (2.71 * 5), loop on reading > the PM timer until it reaches that, and (give or take) you have a 5us delay > that does not depend on the TSC.
4MHz is not actually too bad at all, providing the reading overhead is low - 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/
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