Re^3: Measuring time intervals using Time::HiRes -- time vs. gettimeofday and tv

Vice versa. Look at the Rate column — it shows the speed of the function! The more times a second the function is called, the faster it is :) So in this table (produced by the benchmark involving all three variants)

                   Rate      interval   HiRes::time buitin time()
interval        88470/s            --          -53%          -95%
HiRes::time    188363/s          113%            --          -89%
buitin time() 1753092/s         1882%          831%            --
[download]

builtin time() is 9 times faster than Time::HiRes::time, which is nearly 2 times faster than the weird variant with tv_interval!

Benchmark code is here:

#!/usr/bin/perl

use Time::HiRes;
use Benchmark qw(:all) ;

# Use Perl code in strings...
cmpthese(-1, {
        'interval' => sub { my $t0 = [Time::HiRes::gettimeofday];
                         my $elapsed = Time::HiRes::tv_interval($t0)}
        ,
        'HiRes::time' => sub { my $t0 = Time::HiRes::time();
                         my $elapsed = Time::HiRes::time() - $t0;
        },
        'buitin time()' => sub { my $t0 = time;
                         my $elapsed = time - $t0;
        },
    });
[download]

s;;Just-me-not-h-Ni-m-P-Ni-lm-I-ar-O-Ni;;tr?IerONim-?HAcker ?d;print

Comment on Re^3: Measuring time intervals using Time::HiRes -- time vs. gettimeofday and tv_interval Select or Download Code

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Re^4: Measuring time intervals using Time::HiRes -- time vs. gettimeofday and tv_interval by Tanktalus (Canon) on Jul 18, 2006 at 20:21 UTC
As long as we're all tweaking the heck out of our benchmarks... ;-) What I've noticed is the number of calls to these functions are not all the same. In the 'interval' function, we are calling gettimeofday, constructing an anonymous array, calling tv_interval, and destroying the array. Only one of these are we actually interested in. Meanwhile, both of the other two cases, we're calling *time twice. A completely different set of comparisons. I also eliminated the overhead of returning floats, what little that should be. So, I thought I'd throw this into the mix. Put all the initialisation up front. Then see what happens. Read more... (878 Bytes) And the results? `Rate interval time hires interval 685148/s -- -79% -80% time 3340426/s 388% -- -2% hires 3398163/s 396% 2% --` [download] 2% bonus to hires's time over the built-in time? I'll chalk that up to statistically insignificant, and call the two a tie. In fact, I ran it a second time and got it reversed: `Rate interval hires time interval 971246/s -- -77% -78% hires 4192706/s 332% -- -3% time 4327848/s 346% 3% --` [download] So, I'd say that the difference between interval and time is non-trivial. But even that operates fast enough that I'm not going to worry about it.	[reply] [d/l] [select]

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Re^4: Measuring time intervals using Time::HiRes -- time vs. gettimeofday and tv_interval
by Tanktalus (Canon) on Jul 18, 2006 at 20:21 UTC

As long as we're all tweaking the heck out of our benchmarks... ;-)

What I've noticed is the number of calls to these functions are not all the same. In the 'interval' function, we are calling gettimeofday, constructing an anonymous array, calling tv_interval, and destroying the array. Only one of these are we actually interested in. Meanwhile, both of the other two cases, we're calling *time twice. A completely different set of comparisons. I also eliminated the overhead of returning floats, what little that should be.

So, I thought I'd throw this into the mix. Put all the initialisation up front. Then see what happens.