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.
#! /usr/bin/perl
use warnings;
use strict;
use Time::HiRes qw(time);
use Benchmark qw(:all) ;
my $interval0 = [Time::HiRes::gettimeofday()];
my $hires0 = Time::HiRes::time();
my $time0 = time();
cmpthese(-1,
{
'interval' => sub {
my $elapsed = Time::HiRes::tv_interval($interval0);
return;
},
'hires' => sub {
my $elapsed = Time::HiRes::time() - $hires0;
return;
},
'time' => sub {
my $elapsed = time - $time0;
return;
},
});
And the results?
Rate interval time hires
interval 685148/s -- -79% -80%
time 3340426/s 388% -- -2%
hires 3398163/s 396% 2% --
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% --
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.