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Postings from October 2012
On Tue, Oct 9, 2012 at 11:29 AM, Steffen Mueller <smueller@cpan.org> wrote: > Dear all, > > After reading Reini's blog post, I spent a commute on adding a compile flag > (-DNO_TAINT_SUPPORT) that replaces virtually all taint-related operations > with no-ops. It's in a branch on camel at smueller/no_taint and can't go to > blead quite as-is. > > The upshot is that a the basic script that I had used for profiling function > call overhead now runs somewhere around 10-20% faster. Just compiling > normally, I saw on the order of 18%. With Nicholas' set of "let's try to > avoid alignment issues"[1] flags, I still see 12%. It's a micro-benchmark, > so don't assign too much meaning. Either way, it's *known* to shed > instructions. > .... > Any more sophisticated commetns than Reini's "10% don't matter"? 10% do not matter for me, when I work on the 1000%-2000% level, sorry. Improving speed by 10% disabling taint checks is a nobrainer to me, since the win is minimal, and there are much better optimizations options available. I was talking about 10-20% wins in nextstate, TAINT being the simpliest one. Omitting unneeded resetting the stask, and FREETMPS would be a better win if you target the 10-20% micro-level, since this would not change any functionality. I would rather suggest reading my blog posts about the real wins: aelem, helem, types (no magic, no autovivification) and unneeded stack handling. So far I'm at a 650% faster optimized perl in nbody and 175% in fannkuchredux, but 1000% should be doable. (=10x times faster). That would be 46min down to 4.6m with fannkuchredux 12 and 23min down to 2.3m with nbody 50,000,000. -- Reini Urban http://cpanel.net/ http://www.perl-compiler.org/Thread Previous | Thread Next