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On Sat, Jan 26, 2002 at 01:42:52PM -0800, Linus Torvalds wrote: > > On Sat, 26 Jan 2002, Martin Eriksson wrote: > > > > Hmm.. I tried to compile the kernel with -Os (gcc 2.96-98) and I just got a > > ~1% smaller vmlinux and a ~3% smaller bzImage. > > Note that while "-Os" exists and is documented, as far as I know gcc > doesn't actually do much with it. It really acts mostly as a "disable > certain optimizations" than anything else. > Stupid questions: - what stop us from using -mregparm=3 gcc switch ? - same with -Os -malign-loops=1 -malign-jumps=1 ? - any tool to measure perfomance gain/penalty of above ? > In the 3.0.x tree, it seems to change some of the weights of some > instructions, and it might make more of a difference there. But at the > same time it is quite telling that "-Os" doesn't even change any of the > alignments etc - because gcc developers do not seem to really support it > as a real option. It's an after-thought, not a big performance push. > > Linus > -- Andrey Panin | Embedded systems software engineer pazke@orbita1.ru | PGP key: wwwkeys.eu.pgp.net[unhandled content-type:application/pgp-signature] | |||||||||
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