Recently I stumbled over a handy perl script, which analyzes your currently running apache clients and helps you with tweaking your MPM settings based on calculations:
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| #!/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 ignore the root process. | |
| my $command = 'apache2'; # The name of your processes as they appear to 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 $line[$header{command}]); | |
| if(($line[$header{user}] eq $webuser) && ($line[$header{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{res} | |
| && defined $tempheader{shr} && defined $tempheader{command}) | |
| { | |
| %header = %tempheader; | |
| } | |
| } | |
| } | |
| printf "Total memory available: %.2fG\n", ($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->mean() / 1024); | |
| printf "Recommended number of processes based on Average: %d\n", ($totalmem / $mem->mean()); | |
| printf "Needed memory for 500 processes based on Average: %.2fG\n\n", ($mem->mean() / 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; | |
| } |
The script outputs looks like this:
Total memory available: 7.80G
Total used by apache2 (97 instances): 2.66G
Total used by other processes: 2.57G
Average memory used per apache2 process: 28.03M
Recommended number of processes based on Average: 191
Needed memory for 500 processes based on Average: 13.69G
Max memory used for apache2 process: 45.22M
Recommended number of processes based on Max: 118
Needed memory for 500 processes based on Max: 22.08G
Mean plus two Standard Deviations (bulk of usage under max): 43.11M
Recommended number of processes based on Mean + 2*Stdev: 124
Needed memory for 500 processes based on Mean + 2*Stdev: 21.05G