Hi, I'm David Wang and I'm one of the students that is participating in Google Summer of Code for this summer. My project addresses detecting reference cycles in PHP, and I'm following this discussion because it seems very pertinent to what I will be working with this summer. I'm currently planning on implementing Bacon and Rajan's synchronous cycle collection algorithm based on reference counting. The algorithm requires performing a simple additional task for each increment or decrement of the reference counter. There is a branch in the decrement operation but there is no branch in the increment operation. I wasn't aware that a simple branch such as the one in the proposed patch would incur significant performance penalties on modern superscalar processors, since both execution paths would be followed simultaneously. However, I would also be very grateful for any performance data anyone can provide on this subject (and really, any other advice anyone has!).
The function call does strike me as completely unnecessary and the additional stack operations required are expensive. I'm willing to be that if the function was converted to a macro, the proposed solution would be a workable fix. Just my two cents; I'm not very experienced with the PHP internals yet. Thanks all! David Wang -----Original Message----- From: Stanislav Malyshev [mailto:[EMAIL PROTECTED] Sent: Sunday, May 20, 2007 11:08 PM To: Cristian Rodriguez Cc: internals@lists.php.net Subject: Re: [PHP-DEV] Dismantling the lies... > no, no performance tests has been done over that patch, but as rasmus > said. it is probably negible or acceptable for real world.. I only > knows it works with real like code ( i tried ezpublish, phpmyadmin) > and passes the PHP test suite correctly ( or no worse than without the > patch) Well, php test suite is a functional test, so if the patch is done correctly it'd pass of course. I'm moe worried about the performance - my experience shows that the guesses are often wrong when talked about performance effects in complicated code. If you would have time to run a benchmark using something like bench.php and maybe some more complicated code, it'd be nice to know the result. -- Stanislav Malyshev, Zend Products Engineer [EMAIL PROTECTED] http://www.zend.com/ -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
