Messages in this thread | | | Date | 7 Aug 2006 17:01:08 +0200 | Date | Mon, 7 Aug 2006 17:01:08 +0200 | From | Andi Kleen <> | Subject | Re: [PATCH] Turn rdmsr, rdtsc into inline functions, clarify names |
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On Mon, Aug 07, 2006 at 09:32:29AM -0400, Dmitry Torokhov wrote: > On 8/7/06, Andi Kleen <ak@muc.de> 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. > > > >However it would be some work to implement it for all architectures. > > > > Hmm, would it be easier to export "fast gettimeofday" and assume that > we have slow gettimeofday by default (so gameport will fall back on io > counting)?
I would expect fast gettimeofday to be more common than slow.
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