As already pointed out, it's not exactly clear what you mean, but maybe try something like this:

#!/usr/bin/perl

use GTop ();

my $gtop = GTop->new();

my %pre_stats;

sub get_netstats {
    my $init = shift;
    
    my $netload = $gtop->netload("eth0");
    
    for (qw(bytes_out bytes_in bytes_total
            packets_out packets_in packets_total)) {
        if ($init) {
           $pre_stats{$_} = $netload->$_();
        } else {
            printf "%-14s: %d\n", $_, $netload->$_() - $pre_stats{$_};
        }
    }
}

get_netstats("initial");
system "wget", "http://perlmonks.org";   # your app here
get_netstats();


__END__
$ ./834243.pl
--18:20:17--  http://perlmonks.org/
           => `index.html'
Resolving perlmonks.org... 66.39.54.27, 209.197.123.153
Connecting to perlmonks.org|66.39.54.27|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 83,769 (82K) [text/html]

100%[=================================================================
+==========>] 83,769       118.72K/s             

18:20:18 (118.47 KB/s) - `index.html' saved [83769/83769]

bytes_out     : 3553
bytes_in      : 88978
bytes_total   : 92531
packets_out   : 51
packets_in    : 68
packets_total : 119
[download]

Of course, as the traffic info is interface-global (not process-specific), there mustn't be any other significant network traffic going on while you're measuring...

Thanks. But not able to install the Gtop module in my system. Is this module is applicable for Windows system.In the net It has been said Gtop is used for Unix.

Chances are it will work on windows if libgtop works on windows, and since libgtop is a gnobe library, chances are it might work on windows. :)

Alternatively there is Win32::PerfMon/ Win32::Process::Perf which perform a similar function as libgtop.