#!/usr/bin/perl
# Copyright Erik Jacobson - erik@underhanded.org

use warnings; use strict;
use Statistics::Descriptive;

my $webuser = 'www-data'; # The user your apache children run as.  I i
+gnore the root process.
my $command = 'apache2'; # The name of your processes as they appear t
+o the "top" command.

my @top = `top -bn1`;
my %header;
my $mem = Statistics::Descriptive::Full->new();
my $othermem = Statistics::Descriptive::Full->new();
my $totalmem;

foreach (@top)
{
        s/^\s+|\s+$//sg;
        my @line = split(/\s+/, $_);

        if(/mem:\s+(\S+)\s+total/i)
        {
                $totalmem = convtok($1);
        }

        if(defined $line[3] && exists $header{res} && $line[0] =~ /^\d
++$/)
        {
                next unless (defined $line[$header{user}] && defined $
+line[$header{res}]
                        && defined $line[$header{shr}] && defined $lin
+e[$header{command}]);

                if(($line[$header{user}] eq $webuser) && ($line[$heade
+r{command}] eq $command))
                {
                        $mem->add_data(convtok($line[$header{res}]) - 
+convtok($line[$header{shr}]));
                } else {
                        $othermem->add_data(convtok($line[$header{res}
+]) - convtok($line[$header{shr}]));
                }
        } elsif (!exists $header{res})
        {
                my %tempheader;
                for (0 .. $#line)
                {
                        $tempheader{lc($line[$_])} = $_;
                }

                if(defined $tempheader{user} && defined $tempheader{re
+s}
                        && defined $tempheader{shr} && defined $temphe
+ader{command})
                {
                        %header = %tempheader;
                }
        }
}

printf "Total memory available: %.2fG\n", ($totalmem / 1024 / 1024);
printf "Total used by $command (%d instances): %.2fG\n", $mem->count()
+, ($mem->sum() / 1024 / 1024);
printf "Total used by other processes: %.2fG\n\n", ($othermem->sum() /
+ 1024 / 1024);

$totalmem -= $othermem->sum();

printf "Average memory used per $command process: %.2fM\n", ($mem->mea
+n() / 1024);
printf "Recommended number of processes based on Average: %d\n", ($tot
+almem / $mem->mean());
printf "Needed memory for 500 processes based on Average: %.2fG\n\n", 
+($mem->mean() / 1024 / 1024 * 500);

printf "Max memory used for $command process: %.2fM\n", ($mem->max() /
+ 1024);
printf "Recommended number of processes based on Max: %d\n", ($totalme
+m / $mem->max());
printf "Needed memory for 500 processes based on Max: %.2fG\n\n", ($me
+m->max() / 1024 / 1024 * 500);

printf "Mean plus two Standard Deviations (bulk of usage under max): %
+.2fM\n", (($mem->mean() + $mem->standard_deviation() * 2) / 1024);
printf "Recommended number of processes based on Mean + 2*Stdev: %d\n"
+, ($totalmem / ($mem->mean() + $mem->standard_deviation() * 2));
printf "Needed memory for 500 processes based on Mean + 2*Stdev: %.2fG
+\n", (($mem->mean() + $mem->standard_deviation() * 2) / 1024 / 1024 *
+ 500);

sub convtok
{
        my $num = shift;
        if($num =~ /^\s*([0-9.]+)k\s*$/i)
        {
                $num = $1;
        } elsif ($num =~ /^\s*([0-9.]+)m\s*$/i)
        {
                $num = $1 * 1024;
        } elsif ($num =~ /^\s*([0-9.]+)g\s*$/i)
        {
                $num = $1 * 1024 * 1024;
        }

        return $num;
}