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sj-i/n-body-test-profile-result.md

Last active August 15, 2020 08:36
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profiled https://gist.github.com/Girgias/e21b57cff72b8d05be06883d98552ee6 by using slightly modified version of sj-i/php-profiler,
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n-body-test-profile-result.md

I tested my profiler using https://gist.github.com/Girgias/e21b57cff72b8d05be06883d98552ee6 . The profiler is slightly modified to get information about which opcode is how much used. https://github.com/sj-i/php-profiler/tree/experiment-opcode-tracer

php --version
PHP 7.4.8 (cli) (built: Jul 27 2020 03:41:09) ( ZTS )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies
    with Zend OPcache v7.4.8, Copyright (c), by Zend Technologies
time php ./n-body-test.php 50000000 
sudo ./php-profiler inspector:trace -p 250359 >result
cat result | sort | uniq -c | sort -nr

The output is formatted like below.

[count of appearance in traces] [function] [file]([line])<[opcode]>

  85297 <main> /home/sji/work/test/n-body-test.php(188)<60>
  10369 NBodySystem::advance /home/sji/work/test/n-body-test.php(134)<12>
   2918 NBodySystem::advance /home/sji/work/test/n-body-test.php(138)<28>
   2637 NBodySystem::advance /home/sji/work/test/n-body-test.php(142)<28>
   2184 NBodySystem::advance /home/sji/work/test/n-body-test.php(140)<28>
   2158 NBodySystem::advance /home/sji/work/test/n-body-test.php(144)<28>
   2137 NBodySystem::advance /home/sji/work/test/n-body-test.php(139)<28>
   2130 NBodySystem::advance /home/sji/work/test/n-body-test.php(143)<28>
   2038 NBodySystem::advance /home/sji/work/test/n-body-test.php(130)<82>
   2037 NBodySystem::advance /home/sji/work/test/n-body-test.php(131)<82>
   2006 NBodySystem::advance /home/sji/work/test/n-body-test.php(132)<82>
   1804 NBodySystem::advance /home/sji/work/test/n-body-test.php(128)<45>
   1669 NBodySystem::advance /home/sji/work/test/n-body-test.php(136)<4>
   1661 NBodySystem::advance /home/sji/work/test/n-body-test.php(135)<129>
   1644 NBodySystem::advance /home/sji/work/test/n-body-test.php(134)<1>
   1623 NBodySystem::advance /home/sji/work/test/n-body-test.php(138)<82>
   1611 NBodySystem::advance /home/sji/work/test/n-body-test.php(139)<3>
   1543 NBodySystem::advance /home/sji/work/test/n-body-test.php(138)<3>
   1518 NBodySystem::advance /home/sji/work/test/n-body-test.php(142)<3>
   1515 NBodySystem::advance /home/sji/work/test/n-body-test.php(143)<3>
   1513 NBodySystem::advance /home/sji/work/test/n-body-test.php(140)<3>
   1499 NBodySystem::advance /home/sji/work/test/n-body-test.php(135)<61>
   1493 NBodySystem::advance /home/sji/work/test/n-body-test.php(129)<82>
   1493 NBodySystem::advance /home/sji/work/test/n-body-test.php(128)<20>
   1426 NBodySystem::advance /home/sji/work/test/n-body-test.php(144)<3>
   1418 NBodySystem::advance /home/sji/work/test/n-body-test.php(129)<81>
   1351 NBodySystem::advance /home/sji/work/test/n-body-test.php(144)<82>
   1350 NBodySystem::advance /home/sji/work/test/n-body-test.php(143)<82>
   1305 NBodySystem::advance /home/sji/work/test/n-body-test.php(140)<82>
   1236 NBodySystem::advance /home/sji/work/test/n-body-test.php(139)<82>
   1231 NBodySystem::advance /home/sji/work/test/n-body-test.php(142)<82>
   1231 NBodySystem::advance /home/sji/work/test/n-body-test.php(128)<34>
   1220 NBodySystem::advance /home/sji/work/test/n-body-test.php(130)<2>
   1131 NBodySystem::advance /home/sji/work/test/n-body-test.php(135)<117>
   1114 NBodySystem::advance /home/sji/work/test/n-body-test.php(150)<28>
   1076 NBodySystem::advance /home/sji/work/test/n-body-test.php(149)<28>
   1072 NBodySystem::advance /home/sji/work/test/n-body-test.php(151)<28>
   1050 NBodySystem::advance /home/sji/work/test/n-body-test.php(132)<2>
   1020 NBodySystem::advance /home/sji/work/test/n-body-test.php(126)<78>
   1014 NBodySystem::advance /home/sji/work/test/n-body-test.php(131)<2>
    897 NBodySystem::advance /home/sji/work/test/n-body-test.php(148)<78>
    888 NBodySystem::advance /home/sji/work/test/n-body-test.php(127)<190>
    818 NBodySystem::advance /home/sji/work/test/n-body-test.php(129)<22>
    808 NBodySystem::advance /home/sji/work/test/n-body-test.php(136)<3>
    800 NBodySystem::advance /home/sji/work/test/n-body-test.php(132)<22>
    798 NBodySystem::advance /home/sji/work/test/n-body-test.php(131)<22>
    770 NBodySystem::advance /home/sji/work/test/n-body-test.php(130)<22>
    769 NBodySystem::advance /home/sji/work/test/n-body-test.php(134)<22>
    765 NBodySystem::advance /home/sji/work/test/n-body-test.php(151)<82>
    703 NBodySystem::advance /home/sji/work/test/n-body-test.php(148)<42>
    677 NBodySystem::advance /home/sji/work/test/n-body-test.php(128)<42>
    668 NBodySystem::advance /home/sji/work/test/n-body-test.php(128)<1>
    664 NBodySystem::advance /home/sji/work/test/n-body-test.php(127)<82>
    647 NBodySystem::advance /home/sji/work/test/n-body-test.php(150)<82>
    604 NBodySystem::advance /home/sji/work/test/n-body-test.php(136)<22>
    598 <main> /home/sji/work/test/n-body-test.php(187)<20>
    566 NBodySystem::advance /home/sji/work/test/n-body-test.php(149)<82>
    428 sqrt <internal>(-1)<-1>
    386 NBodySystem::advance /home/sji/work/test/n-body-test.php(151)<3>
    383 NBodySystem::advance /home/sji/work/test/n-body-test.php(150)<3>
    367 NBodySystem::advance /home/sji/work/test/n-body-test.php(126)<22>
    358 NBodySystem::advance /home/sji/work/test/n-body-test.php(149)<3>
    252 <main> /home/sji/work/test/n-body-test.php(188)<112>
    179 NBodySystem::advance /home/sji/work/test/n-body-test.php(153)<62>
    164 NBodySystem::advance /home/sji/work/test/n-body-test.php(124)<63>
    155 NBodySystem::advance /home/sji/work/test/n-body-test.php(126)<82>
    127 NBodySystem::advance /home/sji/work/test/n-body-test.php(148)<82>
    127 NBodySystem::advance /home/sji/work/test/n-body-test.php(148)<77>
    125 NBodySystem::advance /home/sji/work/test/n-body-test.php(148)<127>
    123 NBodySystem::advance /home/sji/work/test/n-body-test.php(126)<127>
    101 <main> /home/sji/work/test/n-body-test.php(187)<34>
     98 NBodySystem::advance /home/sji/work/test/n-body-test.php(126)<77>
     92 <main> /home/sji/work/test/n-body-test.php(188)<116>
      1 printf <internal>(-1)<-1>
      1 <main> /home/sji/work/test/n-body-test.php(190)<129>
      1 <main> /home/sji/work/test/n-body-test.php(190)<112>

According to https://github.com/php/php-src/blob/PHP-7.4.8/Zend/zend_vm_opcodes.h , frequently appeard opcodes are

12: ZEND_POW
28: ZEND_ASSIGN_OBJ_OP
82: ZEND_FETCH_OBJ_R
3: ZEND_MUL
78: ZEND_FE_FETCH_R
22: ZEND_ASSIGN
60: ZEND_DO_FCALL

ZEND_DO_FCALL is the line calls NBodySystem::advance, so it can be ignored to see the result.

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sj-i commented Aug 15, 2020 •
edited

By just using PHP 8.0 beta and JIT, the execution time has been reduced to 1/4 on my machine.
Then replacing X ** 2 to X * X, and move fetching properties of $referenceBody to outside of the most inner loop, the execution time has been reduced to 1/2 from it!

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