Hi, this is sort of a "borderline OT" Perl question, but I was thinking about if it was possible for a single-cpu system to be able to generate identical timestamps using Time::HiRes.

How fast is "fast enough"?

The following script produces substantially different times, when run within the same script. So how fast would my processor have to be, in order to have the numbers be the same? On my 2Ghz single-cpu system, I get anywhere from 20 to 80 ticks difference. Are there any cpus fast enough to make the times identical in this script. Even more curious, could you get identical timestamps from different processes, knowing that the kernel's execution pointer can only be in 1 place at a time, and it takes a few instructions to switch to another process. 

#!/usr/bin/perl
use Time::HiRes qw(gettimeofday);

# Get the timestamp (down to microseconds) 
($secs_since_epoch, $microseconds) = gettimeofday();
print "$secs_since_epoch$microseconds\n";

# Get the timestamp (down to microseconds) 
($secs_since_epoch, $microseconds) = gettimeofday();
print "$secs_since_epoch$microseconds\n";

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In reply to OT How fast a cpu to overwhelm Time::HiRes by zentara

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