Messages in this thread | | | From | (H. Peter Anvin) | Subject | Re: BogoMIPS | Date | 30 Sep 1998 04:20:12 GMT |
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Followup to: <Pine.LNX.3.96.980928175921.21408A-100000@penguin.transmeta.com> By author: Linus Torvalds <torvalds@transmeta.com> In newsgroup: linux.dev.kernel > > > > On Mon, 28 Sep 1998, Richard B. Johnson wrote: > > > > Hmmm. It certainly helps here! It also has helped others who complained! > > I did the same thing for 2.0.x a long time ago. It helped for certain > chips, but it still jittered for others. And it depended on how the kernel > got compiled - there was one (German?) person in particular who took the > bogomips loop into user code and tried it with tons of different > placements, and showed that for his CPU it made a difference how it was > placed and what the surrounding code was. > > As a result, 2.0.x just does it as a separate subroutine in > > arch/i386/lib/delay.S > > and that pretty much forces it to not jitter at all. If you'd send me that > kind of patch I'd accept it. > > Linus >
I think the right thing is to use the TSC if the machine has one (which can be trusted.) That leaves only older, simple machines to use timing loops.
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