Messages in this thread | | | Date | Thu, 30 Dec 1999 00:27:38 +0100 | From | Gabor Lenart <> | Subject | Re: spin_unlock optimization |
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On Wed, Dec 29, 1999 at 07:44:02PM +0100, Oliver Henning wrote: > Hi, > > as was mentioned on Kernel Traffic, the spin_unlock optimization (movb $0,%0 > instead of lock; btrl $0,%0) is not used at last. But could there be a > detection routine (I know this is not a completely new and innovative idea) > for those older PPro CPUs that require the slow version so that in the sane > cases the optimization would be used. At least, IMHO it should be a > compile-time option (defaulting to the slow version) to activate the fast > version.
Yes. Runtime option is not acceptable imho. movb $0,%0 can be fast but if you need a conditional instruction to test if the fast version can be used uses more and more cycles.
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