Hi,
If you're even interested in the tinyest of optimizations, you may wanna
read this. I was just going through the php code. I'm not familiar with it
at all, so I don't know which functions are the bottlenecks, so I can't help
in optimizing the big picture. But I had little else to do right now, so I
figured I'd just browse around through the files to see if I could notice
any local speedups. So really, the things I lay out here are probably
futile, but who knows.
-----
I found that for example the function php_stream_memory_seek() in
main/streams/memory.c contains a whole bunch of return statements. I found
that it can be (you can benchmark this) slightly faster to do this:
int func(int p)
{
int result = 0;
switch (p)
{
case 0: result = 1; break;
case 1: result = -4; break;
case 2: result = 15; break;
}
return result;
}
instead of this:
int func(int p)
{
switch (p)
{
case 0: return 1;
case 1: return -4;
case 2: return 15;
}
return 0;
}
This is correct with 'gcc foo.c' as well as with 'gcc -O2 foo.c'. The
difference is slight, and if it's too tiny, just ignore it this message.
Perhaps some functions that php relies on heavily may benefit from this
though (but I wouldn't know which ones those would be).
-----
Also, I noticed that in php_start_ob_buffer() in main/output.c, and probably
in more functions integers are divided by 2 by doing:
result = intvar / 2;
while it is about 20% faster (even with -O2) to do this:
result = intvar >> 1;
-----
A minor thing I noticed (nothing to speed up here though) is an unused
variable 'i' in insertionsort() in main/mergesort.c (weird that this never
showed up as a compiler warning). Or does the defined TSRMLS_CC depend on
the existance of an integer called 'i'? Pretty unlikely to me.
-----
Why is CONTEXT_TYPE_IMAGE_GIF in main/logos.h defined as "Content-Type:
image/gif" with 2 spaces between "Content-Type" and "image/gif"?
-----
In sapi/apache/mod_php5.c in the function php_apache_log_message(),
Why are these 2 calls:
fprintf(stderr, "%s", message);
fprintf(stderr, "\n");
instead of 1 call:
fprintf(stderr, "%s\n", message);
-----
In sapi/apache/mod_php5.c in the function php_apache_flag_handler_ex(),
the original:
if (!strcasecmp(arg2, "On") || (arg2[0] == '1' && arg2[1] == '\0')) {
bool_val[0] = '1';
} else {
bool_val[0] = '0';
}
is over 5 times slower than:
if (((arg2[0] == 'O' || arg2[0] == 'o') && (arg2[1] == 'n' || arg2[1] ==
'N') && (arg2[2] == '\0')) || (arg2[0] == '1' && arg2[1] == '\0')) {
bool_val[0] = '1';
} else {
bool_val[0] = '0';
}
-----
Like I said, these are extremely tiny things, so please ignore it if it's
too futile :) Nonetheless, if this turns out to be appreciated information,
I'll continue the hunt.
Good luck optimizing,
Ron
"Rasmus Lerdorf" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> 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:
>
> <html>
> <?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 $a->getProp();
> echo <<<EOB
> The database is {$config['db']}
> and the user is {$config['db_user']}
>
> EOB;
> ?>
> </html>
>
> 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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