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Date: Mon, 04 Oct 2004 16:59:28 -0700
To: Sebastian Bergmann <sb@sebastian-bergmann.de>,internals@lists.php.net
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Subject: Re: [PHP-DEV] GCC/CFLAGS Benchmark for HEAD and PHP_5_0
From: andi@zend.com (Andi Gutmans)
References: <cjs4sr$kkh$1@sea.gmane.org>

I've done lots of testing with these kind of compiler flags. It's really a 
tough call because you might change 2 lines in the PHP code and then your 
results might differ completely because of CPU cache hits/misses. Also very 
much depends on the CPU.
But in any case, interesting results.

Andi

At 08:30 PM 10/4/2004 +0200, Sebastian Bergmann wrote:
>  I ran the Zend/bench.php script with PHP 5.0 and PHP 5.1 compiled with
>  GCC 3.3 and GCC 3.4 using different optimizations on my Intel Pentium-M
>  laptop:
>
>   HEAD (PHP 5.1.0-dev)
>
>     GCC 3.3.4 (-march=pentium3)
>
>       -O0:                          48.602
>       -Os:                          29.920
>       -O1:                          31.349
>       -O2:                          29.029
>       -O3:                          29.644
>
>     GCC 3.4.2 (-march=pentium-m -mtune=pentium-m)
>
>       -O0:                          48.966
>       -Os:                          26.286
>       -O1:                          29.253
>       -O2:                          29.100
>       -O3:                          27.767
>
>       -fprofile-{generate|use} -Os: 24.216
>       -fprofile-{generate|use} -O1: 26.575
>       -fprofile-{generate|use} -O2: 26.339
>       -fprofile-{generate|use} -O3: 25.537
>
>
>   PHP_5_0 (PHP 5.0.3-dev)
>
>     GCC 3.3.4 (-march=pentium3)
>
>       -O0:                          58.394
>       -Os:                          42.570
>       -O1:                          43.454
>       -O2:                          42.092
>       -O3:                          42.066
>
>     GCC 3.4.2 (-march=pentium-m -mtune=pentium-m)
>
>       -O0:                          59.272
>       -Os:                          35.853
>       -O1:                          38.275
>       -O2:                          37.989
>       -O3:                          41.020
>
>       -fprofile-{generate|use} -Os: 33.926
>       -fprofile-{generate|use} -O1: 36.853
>       -fprofile-{generate|use} -O2: 35.335
>       -fprofile-{generate|use} -O3: 38.897
>
>  For the -fprofile-{generate|use} builds I used the Zend/bench.php
>  script, too, to generate the profile information. If we were to add
>  Makefile target (like GCC itself ("make profiled-bootstrap")) to the
>  PHP build that makes use of -fprofile-{generate|use} it would make
>  sense to use "make test" to generate the profiling information.
>
>  When I find the time I will repeat the benchmark on my AMD Athlon64 box
>  because I think the small L1/L2 caches of the laptop CPU affect the
>  performance of the bigger code generated through optimizations. You can
>  clearly see that code optimized for size (-Os) is faster than the more
>  aggressive -O1, -O2, and -O3 optimization levels.
>
>--
>Sebastian Bergmann                      http://www.sebastian-bergmann.de/
>GnuPG Key: 0xB85B5D69 / 27A7 2B14 09E4 98CD 6277 0E5B 6867 C514 B85B 5D69
>
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