Hi, I had lots of loop in my code. My gain was %4 to %6 and I say "may gain another %10". Of course your millage was different than me Regards Sancar On Saturday 21 July 2007 01:03:45 Richard Lynch wrote: > On Fri, July 20, 2007 4:16 am, Colin Guthrie wrote: > > Sancar Saran wrote: > >> Another simple performance tip. > >> > >> Most of for examples of php look like this > >> for($x=0;$x<sizeof($arrSometing);$x++) > >> > >> This is bad. In every cycle you call sizeof > >> > >> this was good > >> $intSize = sizeof($arrSometing); > >> for($x=0;$x<$intSize;$x++) > >> > >> if u use. > >> for($x=0;$x<$intSiz;++$x). You may gain another %10 > >> > >> to determine costs of your functions use xdebug and kcachegrind. > > > > I've always used pre-increment in loops like you suggest as it was an > > ingrained part of my C/C++ learning from a performance perspective. I > > wasn't sure if the same was true in PHP but you seem to suggest it is, > > so I feel justified now :) > > I don't really care if one uses pre or post, but I just benchmarked > this, and I don't really think it makes a 10% win. > > And I had to crank it up to 10 MILLION to get any kind of realistic > measurable time in the first place. > > How often do you have a PHP loop that runs to 10 MILLION iterations?! > > Note that I did three with pre before post tests and three post before > pre tests to even out any caching effects. > > Test environment details at the bottom. > > sagacitydev@ch10106cus002 ~/junk $ cat pre.php post.php > <?php > for ($i = 0; $i < 10000000; ++$i); > ?> > <?php > for ($i = 0; $i < 10000000; $i++); > ?> > sagacitydev@ch10106cus002 ~/junk $ time php -q pre.php ; time php -q > post.php > > real 0m5.422s > user 0m5.350s > sys 0m0.070s > > real 0m5.397s > user 0m5.330s > sys 0m0.070s > sagacitydev@ch10106cus002 ~/junk $ time php -q pre.php ; time php -q > post.php > > real 0m5.164s > user 0m5.090s > sys 0m0.070s > > real 0m5.310s > user 0m5.230s > sys 0m0.080s > sagacitydev@ch10106cus002 ~/junk $ time php -q pre.php ; time php -q > post.php > > real 0m5.093s > user 0m5.030s > sys 0m0.070s > > real 0m5.387s > user 0m5.300s > sys 0m0.080s > sagacitydev@ch10106cus002 ~/junk $ time php -q post.php ; time php -q > pre.php > > real 0m5.429s > user 0m5.340s > sys 0m0.070s > > real 0m5.140s > user 0m5.060s > sys 0m0.080s > sagacitydev@ch10106cus002 ~/junk $ time php -q post.php ; time php -q > pre.php > > real 0m5.348s > user 0m5.270s > sys 0m0.070s > > real 0m5.101s > user 0m5.030s > sys 0m0.070s > sagacitydev@ch10106cus002 ~/junk $ time php -q post.php ; time php -q > pre.php > > real 0m5.376s > user 0m5.300s > sys 0m0.080s > > real 0m5.009s > user 0m4.910s > sys 0m0.100s > > sagacitydev@ch10106cus002 ~/junk $ php -v > PHP 4.4.7 (cli) (built: May 8 2007 09:49:19) > Copyright (c) 1997-2007 The PHP Group > Zend Engine v1.3.0, Copyright (c) 1998-2004 Zend Technologies > > sagacitydev@ch10106cus002 ~/junk $ uname -a > Linux ch10106cus002 2.6.18-hardened-r6 #2 SMP Tue Apr 17 09:15:05 CDT > 2007 i686 Dual Core AMD Opteron(tm) Processor 270 AuthenticAMD > GNU/Linux > sagacitydev@ch10106cus002 ~/junk $ > > Perhaps the OP meant that not doing the count() / sizeof() on every > iteration was a 10% win? Now *THAT* I can believe! > > -- > Some people have a "gift" link here. > Know what I want? > I want you to buy a CD from some indie artist. > http://cdbaby.com/browse/from/lynch > Yeah, I get a buck. So? -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
