On Mon, Jan 17, 2022, at 6:12 AM, Dmitry Stogov wrote: > Oh, probably this is just the biggest prime number that fits into a signed > 16-bit number :)
Seems like the sort of thing that should be documented inline. (Also, why it needs to be a prime number.) --Larry Garfield > On Mon, Jan 17, 2022 at 10:49 AM Su, Tao <tao...@intel.com> wrote: > >> Thanks Dmitry for the information. >> >> With a few debug sessions, I found that 32531 is working well >> for any thresholds, and is also a big prime number :-). >> >> >> -----Original Message----- >> From: Dmitry Stogov <dmitrysto...@gmail.com> >> Sent: Monday, January 17, 2022 1:37 PM >> To: Su, Tao <tao...@intel.com> >> Cc: PHP internals <internals@lists.php.net> >> Subject: Re: [PHP-DEV] Reason for ZEND_JIT_COUNTER_INIT set to 32531? >> >> This it's my choice. >> This number is common for all JIT counters (hot_loop, hot_func, >> hot_return). >> It's value was selected to provide the best precision when different >> counters have different thresholds. >> Unfortunately, I can't remember the exact equations or logic I used at >> that time. >> >> Thanks. Dmitry. >> >> On Thu, Jan 13, 2022 at 1:01 PM Su, Tao <tao...@intel.com> wrote: >> >> > Hi Internal, >> > I am not sure this is a correct mail list for asking source code >> > related question. >> > If not, I am sorry. Appreciate you guys' help. >> > >> > I am reading PHP8 JIT related source code and found that zend_jit.h >> > has a magic definition ZEND_JIT_COUNTER_INIT as 32531 which I do not >> > quite understand how this number was chosen and why? >> > Anybody can provide some historic information? >> > #define ZEND_JIT_COUNTER_INIT 32531 >> > >> > A code example using this definition (looks like the 2nd parameter >> > computes into a fixed number if hot_func is set by php.ini) >> > ZEND_OPCODE_TAIL_CALL_EX(zend_jit_trace_counter_helper, >> > ((ZEND_JIT_COUNTER_INIT + JIT_G(hot_func) - 1) / >> > JIT_G(hot_func))); >> > >> > >> > ======================================= >> > Tony Su (Su, Tao) >> > make a 'lazy' programmer diligently with efficiency >> > >> > >> -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: https://www.php.net/unsub.php
