Messages in this thread | | | Date | Tue, 12 Jun 2007 12:18:00 +1000 | From | Nick Piggin <> | Subject | Re: why does the macro "ZERO_PAGE" take an argument? |
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H. Peter Anvin wrote: > William Lee Irwin III wrote: > >>Robert P. J. Day wrote: >> >>>>although it's not clear where in the source tree are the invocations >>>>that would actually make a difference to a MIPS system, which is why >>>>i've CC'ed ralf on this. i'm sure he can clear this up. :-) >> >>On Thu, Jun 07, 2007 at 10:32:29AM -0700, H. Peter Anvin wrote: >> >>>x86 could also benefit from coloured zeropages. In fact, I thought it >>>already had them (K8 wants as many as 8.) >> >>How would one demonstrate the beneficial effect of such? > > > Dean Gaudet at Transmeta did some benchmarking using SPEC. If I recall > his numbers correctly (this is from memory, mind you) on Transmeta > Efficeon, which has 2-way virtual cache tagging with hardware recovery, > zeropage coloring was a 1.5% performance improvement.
I'm surprised that the benchmark made such use of zero pages so as to be worthwhile. I'm sitting on a patch which removes the zero page from the page fault fastpath completely which I'd like to try out in -mm...
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