RE: [PHP-DEV] messing with branch prediction
| From: | Leon Matthews | Date: | Mon, 19 Jun 2006 21:13:41 +0000 |
| Subject: | RE: [PHP-DEV] messing with branch prediction | ||
| References: | 1 | Groups: | php.internals |
| Request: | Send a blank email to internals+get-24157@lists.php.net to get a copy of this message | ||
> Andi Gutmans wrote:
> I think it's a nice idea but I doubt it's very useful at this point. It
> doesn't seem to significantly affect performance, which is ... <snip>
I concur.
Instead of guessing branch probabilities, why not measure them?
http://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/Optimize-Options.html
-fprofile-generate
-freorder-functions
-fbranch-probabilities
-fprofile-use
I've seen decent speedups (5-10%) using these options on my own programs.
Leon