On Friday 27 March 2009 15:37:31 Jamie Lokier wrote: > Thomas Häberle wrote: > > All used CPUs have a MMU, but it is not used due to performance > > reasons as the developers state. Someone threw a number into the > > discussion and said enabling the MMU would cause performance losses > > of about 30-40 percent, thus if we switch to Linux at all it would > > have to be ucLinux. > > That's a very large performance loss for an MMU. > > It's possible depending on the implementation. Most MMUs use a TLB > (which caches MMU lookups) and virtually-indexed instruction/data > caches so there's little or no cost to cache hits. If the TLB is too > small it might cause a significant performance loss. > > I have heard of a paper which says enabling the MMU on some ARM CPUs > was a significant performance loss, but I've never read it.
i'm pretty sure it's this paper: http://opensrc.sec.samsung.com/document.html -mike _______________________________________________ uClinux-dev mailing list uClinux-dev@uclinux.org http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by uclinux-dev@uclinux.org To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev
