Messages in this thread | | | Date | Mon, 7 Aug 2006 15:18:34 +0200 | From | Vojtech Pavlik <> | Subject | Re: [PATCH] Turn rdmsr, rdtsc into inline functions, clarify names |
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On Mon, Aug 07, 2006 at 02:56:39PM +0200, Andi Kleen wrote: > On Mon, Aug 07, 2006 at 02:48:55PM +0200, Vojtech Pavlik wrote: > > On Mon, Aug 07, 2006 at 02:28:45PM +0200, Andi Kleen wrote: > > > On Mon, Aug 07, 2006 at 01:09:31PM +0200, Vojtech Pavlik wrote: > > > > On Mon, Aug 07, 2006 at 10:48:50AM +0200, Andi Kleen wrote: > > > > > On Sun, Aug 06, 2006 at 10:43:44PM -0400, Dmitry Torokhov wrote: > > > > > > On Saturday 05 August 2006 23:16, Andi Kleen wrote: > > > > > > > This whole thing is broken, e.g. on a preemptive kernel when the > > > > > > > code can switch CPUs > > > > > > > > > > > > > > > > > > > Would not preempt_disable fix that? > > > > > > > > > > Partially, but you still have other problems. Please just get rid > > > > > of it. Why do we have timer code in the kernel if you then chose > > > > > not to use it? > > > > > > > > The problem is that gettimeofday() is not always fast. > > > > > > When it is not fast that means it is not reliable and then you're > > > also not well off using it anyways. > > > > I assume you wanted to say "When gettimeofday() is slow, it means TSC is > > not reliable", which I agree with. > > > > But I need, in the driver, in the no-TSC case use i/o counting, not a > > slow but reliable method. And I can't say, from outside the timing > > subsystem, whether gettimeofday() is fast or slow. > > Hmm if that is the only obstacle I can export a "slow gettimeofday" flag.
That would help.
> However it would be some work to implement it for all architectures. > > > I assume we could make it work with the monotonic timer instead. > > The monotonic timer is the right thing to use to make you independent > of ntpd, but it's normally not faster or slower than gettimeofday.
Yup.
-- Vojtech Pavlik Director SuSE Labs - 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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