messing with branch prediction

From: Date: Sun, 18 Jun 2006 13:49:47 +0000
Subject: messing with branch prediction
Groups: php.internals 
Request: Send a blank email to internals+get-24149@lists.php.net to get a copy of this message
Hello, Yesterday I was playing with branch prediction in the Zend VM executor. Although I didn't have any noticeable performance improvement within the bench.php script, I've put the patch on-line, because someone else might want to mess with it too :) (but with care..) patch: http://mega.ist.utl.pt/~ncpl/zend_branch_prediction.txt gcc docs: http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-g_t_005f_005fbuiltin_005fexpect-2440 the zend.h part of the patch is based on the similar macros (with the same name, too) found in the Linux kernel. I made & tested the patch in a Centrino laptop with gcc 3.4, so it might be the cause of getting no relevant performance increase. On CPUs with longer pipelines (like Pentium 4/NetBurst architecture), the performance increase might be noticeable. Happy hacking :) Nuno

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