Update: Time::HiRes does use the high performance counters internally, in the lastest CPAN version anyway. I'm not sure why the version I have produces such low resolution output?

The tick counter that Time::HiRes uses on Win32 isn't that hi res as you've seen. 64/second under NT4/5 and lower on earlier systems.

There are however much higher resolution timers available.

On my system these have a resolution of 1/3,579,545 times a seconds which is much faster than you can query them, even in C. On a single processor machine this should be sufficient to ensure uniqueness. On a multi-processor machine there is a small chance that two threads or processes could get exactly the same number, but combining that with the process/thread ID should suffice.

Update: If you have Time::HiRes v1.59, this code should be redundant!

Some code to show how to get at and convert the high resolution timer:

#! perl -slw
use strict;
use Win32::API::Prototype;

ApiLink( 'kernel32', q[
    BOOL QueryPerformanceCounter( LARGE_INTEGER *lpPerformanceCount )
]) or die $^E;

ApiLink( 'kernel32', q[
    BOOL QueryPerformanceFrequency( LARGE_INTEGER *lpPerformanceCount 
+)
]) or die $^E;

sub int64_to_NV {
    my( $lo, $hi ) = unpack 'VV', $_[ 0 ];
    return $hi * 2**32 + $lo;
}

my $frequency = ' ' x 10;
QueryPerformanceFrequency( $frequency ) or die $^E;

print 'Counter changes ', int64_to_NV( $frequency ), ' times/second';

for ( 1 .. 10 ) {
    QueryPerformanceCounter( $frequency )or die $^E;
    print int64_to_NV( $frequency );
}
__END__
P:\test>375475
Counter changes 3579545 times/second
699092440218
699092440527
699092440794
699092441059
699092441312
699092441566
699092441820
699092442073
699092442322
699092442576
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