Messages in this thread | | | Date | Sat, 21 Dec 2002 23:26:22 -0200 | From | Arnaldo Carvalho de Melo <> | Subject | Re: Kernel GCC Optimizations |
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Em Sat, Dec 21, 2002 at 07:20:28PM -0600, scott thomason escreveu: > On Saturday 21 December 2002 04:10 pm, folkert@vanheusden.com wrote: > > > > Is there any risk using -O3 instead of -O2 to compile the > > > > kernel, and why? > > > > > > * It might uncover subtle bugs that would otherwise not occur. > > > > I wonder: for the sake of performance and good use of the precious > > clock- cycles, shouldn't there be made a start of fixing those > > bugs? Assuming that the bugs you're talking about are not > > compiler-bugs, they *are* bugs in the code that should be fixed, > > shouldn't they? > > > > > * Compiling with unusual options means that less people will know > > > about any problems it causes you. > > > > So, let's make it -O6 per default for 2.7.x/3.1.x? > > Let's not. I'd rather have the best kernel developers concentrating on > finishing important kernel features rather than digging their way out > of esoteric optimizer debugging sessions only to find it was a flaw > in gcc. The difference in performance boost between -O2 and greater > levels isn't usually enough to make a significant impact, not as > significant as the introduction of important new features, for > example.
Sometimes even _reducing_ the optimization for performance level makes it faster, try with -Os. And this was already discussed here and elsewhere, reading the archives would help a lot avoiding adding more noise to the list.
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