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Postings from February 2003
On Tue, Feb 11, 2003 at 09:24:21AM +0100, A. Bergman wrote: > > On måndag, feb 10, 2003, at 23:03 Europe/Stockholm, > perl5-porters-return-71692-arthur=contiller.se@perl.org wrote: I've never heard myself called that before :-) > >This is probably the right default for the general case, but it is > >counterproductive for benchmarking small code changes. So on gcc 2.95 > >I'm > >compiling with: > > > >-O -malign-loops=3 -malign-jumps=3 -malign-functions=3 > >-mpreferred-stack-boundary=3 -march=i686 > > > >(thats 2**3, ie 8) > > > >and on gcc 3.2 on a different machine: > >-O3 -falign-loops=16 -falign-jumps=16 -falign-functions=16 > >-mpreferred-stack-boundary=3 -march=i586 > > > > Does compiling with these settings make general perl faster? No. all together about 2% slower, at least according to perlbench. I'm not that surprised. I didn't experiment with trying each independently, as I was looking for deterministic benchmarks when code changed slightly, rather than a faster speed from aggressive compiler options. I expect that the loop alignment forcing options will only really help on the tight loops, such as the substring finding loop, or hashing loop, although the hashing loop is inlined everywhere it is needed, so that's a pain. If someone has the time they could experiment with which options might help, and whether pulling some code out into a separate file that benefits from (say) loop alignment helps measurably. Although I suspect that anyone with time to do this would be better spending it making better benchmarks. Nicholas ClarkThread Previous | Thread Next