in reply to Timer implementation

What is the application? What time resolution do you need? What is the code you have tried?

Perl reduces RSI - it saves typing

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Re^2: Timer implementation
by bash (Scribe) on Sep 16, 2008 at 02:20 UTC
    My application is cgi script. I need at least milli-second. My code is very simple. At case of times(). I use: 
    
$start = [times()];
...somecode...
$end = [times()];


$time_diff =($start->[0] + $start->[1]) - ($end->[0] + $end->[1]);

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    at case of Time::HiRes 
    $start=[gettimeofday];
...somecode...
$end = [gettimeofday];

$time_diff = tv_interval($start, $end);

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    But if real <=> sys+user, my first case will be always lower that at case 2
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[d/l]
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      Your implementation context is CGI script, but that is not your application. Your application may be timing a database query or some such. So, what is the application?

      You need to decide what it is that you want to report - wall clock time or process time.

      With most operating systems that are not designed for real time environments reporting wall clock times of less than a few milliseconds is fairly meaningless because time slices for tasks are of that order and will render any real time reporting at that level meaningless.

      Perl reduces RSI - it saves typing
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        My application is CGI script that works with SQLite and does a lot of text manipulation works.
        Of course i need wall clock to know is it my script works so slowly or it is slow network throughput.
        If script works slowly, then i will know that i need to do some code optimization.
        But if i got situation where real time is much more bigger than sys+real time. What to do in this case? And is it possible case? If I understand correctly it's possible at case where CPU is busy by other process or my process is sleeping on I/O system calls. If it's true - robust timer should include all three number - real, system and user times. Am i right?
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