On 3/8/08, Gregory Beaver <[EMAIL PROTECTED]> wrote:
> Hi,
>
> When I posted yesterday's patch to add stream support to include_path
> (http://news.php.net/php.internals/36031) I mentioned that I suspected
> benchmarking would reveal it to be slow. My primary goal is to provide
> no impact on current users who are using a traditional include_path,
> with a secondary goal of improving performance of those who use the new
> syntax. Today I ran callgrind on the thing, with some surprising results.
>
> With the patch, include is *faster* for our traditional users than it is
> now.
> With the patch, include_once with >1000 unique files is about 3% slower
> - not the whole execution, just include_once
> With the patch, include_once with 1 unique file included 1 times is
> insignificantly slower (about 0.4%)
>
> For these reasons, I'm really encouraged :). The next step is to
> absolutely ensure correctness and then see if the streams part of
> include_path can be optimized at all (or if it needs it).
>
> Details
> ==
>
> I just ran callgrind on this script:
>
>
> set_include_path('.:/usr/local/lib/php:/home/cellog/workspace/php5/ext/phar');
> for ($i = 0; $i < 10; $i++) {
> include 'extra.php';
> }
>
> The empty file "extra.php" (zero byte) is in
> "/home/cellog/workspace/php5/ext/phar/extra.php" ensuring that we
> traverse include_path to find it.
>
> To my great shock, the script runs *faster* with my patch, because it
> executes significantly more instruction cycles in
> php_stream_open_for_zend_ex without the patch.
>
> Note that this does not measure the cost of *_once. *_once is a lot
> harder to measure, so I created 10,000 files (yikes) via this script:
>
>for ($i = 1; $i <= 1; $i++) file_put_contents('test' . $i, '');
>
> and then ran this test script:
>
>set_include_path('.:/usr/local/lib/php:/home/cellog/workspace/php5/poop');
> for ($i = 1; $i <= 1; $i++) {
> include_once 'test' . $i;
> }
>
> callgrind reported that php_resolve_path was about twice as slow as the
> other version, resulting in a 3% degradation of include_once performance
> over the current version (which is much faster than 5.2.x, incidentally).
>
> Finally, to test the _once aspect of include_once, I ran this script:
>
>
> set_include_path('.:/usr/local/lib/php:/home/cellog/workspace/php5/ext/phar');
> for ($i = 0; $i < 10; $i++) {
> include_once 'extra.php';
> }
>
> With this script, it really highlights the most common use case of
> include/require_once: attempting to include the same file multiple
> times. The difference in performance was insignificant, with callgrind
> reporting a total execution portion of 75.12% for CVS, and 75.57% with
> my patch.
>
> So, it looks like the biggest performance hit would be for users
> including more than 1000 different files, and would result in
> approximately 3% slower performance *of include_once*. I'm curious how
> many of our readers have a PHP setup that includes close to this many
> files, because it seems rather unlikely to me that anyone would include
> more than a few hundred in a single process.
>
> The surprising news is that users who are using "include" would see a
> performance improvement from my patch, so I recommend that portion be
> committed regardless of other actions. This improvement proabbly
> results from removing an include_path search in plain_wrapper.
what about including(_once) by absolute path?
--
Alexey Zakhlestin
http://blog.milkfarmsoft.com/
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