On Tue, 2002-11-05 at 17:38, Thomas Dodd wrote: > > > Jean Francois Martinez wrote: > > > I wrote a numerical analysis who was published in february 1999 and > > Is that available online? > www.linuxgazette.com february 1999 > > basically you don't gain 5%. It is closer to 1.5% to 2.5% and this > > when you are running kernel code (when you are running user mode code > > it is unaffected). And since 2002 machines are much bigger than the > > 32 meg box I used as an example the memory savings brought by a kernel > > compile are still more irrelevant > > What compiler? gcc-3 is supposed to have better optimization. > Perhaps the numbers would be different now? > It was gcc 2.7. But while gcc has changed so have the distributions: at that time distros shipped only one kernel since gcc 2.7 performed very little processor-specific optimizations and there was very little code in the kernel directly related to processor type (the memcpy code, page protection and selective invalidation of TLB entries). Today this is no longer valid but RedHat ships processor-specific kernels You _could_ gain a benefit if you are still using a Pentium MMX or a K6: both will get a Pentium kernel and code optimized for Pentium will suck on anything else MMX included. For the K6 I recommend hacking the compiler flags and using -mcpu=i686 (NOT -march=i686) instead of -march=k6 . Gcc generates some slow code when told to optimize for the K6 specially on bit operations who are frequently used in kernel. But MMX and K6 are now quite rare. JFM -- Psyche-list mailing list Psyche-list@redhat.com https://listman.redhat.com/mailman/listinfo/psyche-list
