tail from GNU coreutils has an option for controlling the sleep time between reads: 
-s, --sleep-interval=S
  with -f, sleep for approximately S seconds (default 1.0) between ite
+rations

[download]
And if you really want to follow a rapidly growing file (for instance some timing sensitive log without proper timestamps) with a lot finer time resolution than probably you appreciate the File-Tail module from CPAN. This modules adapts its sleep interval to the line-update frequency measured before. (Of course if you don't have control on the buffering at output side, this still won't be better.) An example: 

# generate test log file in bash
$ while true ; do echo $(( ++i )) ; sleep .1 ; done > test

[download]

# little File::Tail demo
use Time::HiRes qw( gettimeofday );
use File::Tail;

$| = 1;

my $tail = File::Tail->new( name => './test', maxinterval => 0.1 );

my $usec;
my $sec_since_epoch;
my $line;

while ( defined( $line = $tail->read() ) ) {
  ( $sec_since_epoch, $usec ) = gettimeofday();
  printf "%d.%d\n", $sec_since_epoch, $usec;
}

[download]

In reply to Re: Time::HiRes strange behavior by rubasov
in thread Time::HiRes strange behavior by golden.radish

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