in reply to Time::HiRes sleep does not always work

Which version of Time::HiRes are you using?

There was a bug in versions < ~1.53 that meant it only used a low-resolution timer. This what later enhanced with the use of a short period, high resolution timer.

However, there were still some circumstances, particularly under the aucpices of the debugger, in which the resolution seemed to fall off quite badly. See In search of a bug in Time::HiRes on Windows..

You mentioned Vista somewhere in one of your replies. Are all the systems running Vista? Maybe there is some incompatibility.

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In the absence of evidence, opinion is indistinguishable from prejudice.
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  • Comment on Re: Time::HiRes sleep does not always work

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Re^2: Time::HiRes sleep does not always work
by tone (Novice) on Aug 18, 2008 at 13:04 UTC

    I'm using version 1.9712

    Out of the five systems I tested on only one is running Vista and all the others are on XP.

[reply]

      Could you post the output from the following on one machine that gives good results and one that gives bad: 

      #! perl -slw
use strict;
use Time::HiRes qw[ gettimeofday time ];

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 'QPC: ',int64_to_NV( $frequency );
}


printf "GToD: %.8f\n", scalar gettimeofday() for 1 .. 10;
printf "Time: %.8f\n", time() for 1 .. 10;

      [download]
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]

        If I run your script on my machine (bad) I get:

        Counter changes 3579545 times/second
QPC: 35752003971
QPC: 35752004170
QPC: 35752004356
QPC: 35752004527
QPC: 35752004695
QPC: 35752004854
QPC: 35752005017
QPC: 35752005169
QPC: 35752005333
QPC: 35752005487
GToD: 1219149309.90625000
GToD: 1219149309.90625000
GToD: 1219149309.90625000
GToD: 1219149309.90625000
GToD: 1219149309.90625000
GToD: 1219149309.90625000
GToD: 1219149309.90625000
GToD: 1219149309.90625000
GToD: 1219149309.90625000
GToD: 1219149309.90625000
Time: 1219149309.90625000
Time: 1219149309.90625000
Time: 1219149309.90625000
Time: 1219149309.90625000
Time: 1219149309.90625000
Time: 1219149309.90625000
Time: 1219149309.90625000
Time: 1219149309.90625000
Time: 1219149309.90625000
Time: 1219149309.90625000

        [download]

        And here is the output from a "good" machine:

        Counter changes 3579545 times/second
QPC: 76031246430
QPC: 76031246657
QPC: 76031246790
QPC: 76031247127
QPC: 76031247273
QPC: 76031247479
QPC: 76031247686
QPC: 76031247838
QPC: 76031247972
QPC: 76031248165
GToD: 1219150762.25000000
GToD: 1219150762.25004410
GToD: 1219150762.25007610
GToD: 1219150762.25010900
GToD: 1219150762.25013900
GToD: 1219150762.25017500
GToD: 1219150762.25020500
GToD: 1219150762.25024100
GToD: 1219150762.25027490
GToD: 1219150762.25030590
Time: 1219150762.25033810
Time: 1219150762.25036690
Time: 1219150762.25039600
Time: 1219150762.25042800
Time: 1219150762.25047900
Time: 1219150762.25053190
Time: 1219150762.25058200
Time: 1219150762.25063110
Time: 1219150762.25066710
Time: 1219150762.25069900

        [download]
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