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Date: Sun, 12 Mar 2006 21:17:26 -0800
To: Rasmus Lerdorf <rasmus@lerdorf.com>,internals <internals@lists.php.net>
In-Reply-To: <4414F63F.5030406@lerdorf.com>
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Subject: Re: [PHP-DEV] Calling performance geeks
From: andi@zend.com (Andi Gutmans)

What are the results you're getting on an empty script? I'm just 
curious whether it's execution speed or startup speed where you are 
seeing the big hit. There were changes in both which might have 
slowed things down. Another reason to be more careful re: bloat :)

Anid

At 08:34 PM 3/12/2006, Rasmus Lerdorf wrote:
>We have a bit of a performance disconnect between 4.4 and 5.1 
>still.  I was doing some benchmarking today just as a sanity check 
>on some APC work I have been doing lately and came up with this:
>
>   http://lerdorf.com/php/bm.html
>
>You can ignore the apc/eaccelerator stuff.  Those numbers are not 
>surprising.  The surprising number to me is how much faster 4.4 still is.
>
>The graph labels are slightly off.  The 0, 5 and 10 includes should 
>really be 1, 6 and 11.  The actual benchmark code is here:
>
>   http://www.php.net/~rasmus/bm.tar.gz
>
>Tested on a Linux 2.6 Ubuntu box on an AMD chip (syscalls are cheap 
>there) with current PHP_4_4 and PHP_5_1 checkouts.  Was also testing 
>5.1.2 to see the effect of getting rid of that uncached realpath call.
>
>As far as I can tell auto_globals_jit isn't working at all, but I 
>eliminated that by doing variables_order = GP for these benchmarks. 
>Even so, the request_startup is significantly more expensive in 5.1.
>
>Here are callgrind dumps for each.  Load them up with kcachegrind 
>and browse around:
>
>PHP 4.4  http://www.php.net/~rasmus/callgrind.out.1528.gz
>PHP 5.1  http://www.php.net/~rasmus/callgrind.out.1488.gz
>
>Each of these is 1000 requests against the top.php and 4top.php 
>scripts.  from bm.tar.gz.  If you start at the
>
>The script is trivial and looks like this:
>
><?php $base_dir = '/var/www/bm/'; include $base_dir . 'config.inc'; 
>function top_func($arg) { $b = $arg.$arg; echo $b; } class top_class 
>{ private $prop; function __construct($arg) { $this->prop = $arg; } 
>function getProp() { return $this->prop; } function setProp($arg) { 
>$this->prop = strtolower($arg); } } top_func('foo'); $a = new 
>top_class('bar'); echo $a->getProp(); $a->setProp("AbCdEfG"); echo 
>$a->getProp(); echo <<
>and config.inc is:
>
><?php
>$config = array(
>    'db'      => 'mysql',
>    'db_user' => 'www',
>    'db_pwd'  => 'foobar',
>    'config1' => 123,
>    'config2' => 456,
>    'config3' => 789,
>    'sub1'    => array(1,2,3,4,5,6,7,8,9,10),
>    'sub2'    => array("abc","def","ghi","jkl","mno","pqr","stu","vwx","yz")
>);
>?>
>
>4top.php is identical except for the class definition being PHP 4-style
>instead.  As in no private and a PHP 4 constructor.  Otherwise it is
>identical.
>
>I have some ideas for things we can speed up in 5.1.  Like, for example,
>we should add the ap_add_common_vars() and ap_add_cgi_vars() to the jit
>mechanism.  There isn't much point filling these in unless the script
>tries to get them.  the ap_add_common_vars() call is extremely expensive
>since it does a qsort with a comparison function that uses strcasecmp.
>Of course, this same optimization can be done in 4.4.
>
>If you know your way around kcachegrind, load up the two callgrind files
>and see what stands out for you.  As far as I can tell, while we can do
>some tricks to speed up various helper bits, the slowdown is coming from
>the executor trashing its cache lines.
>
>-Rasmus
>
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