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. -- Jamie _______________________________________________ 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
