This web page provides the details for the data that gives this graph:
The experiment was done on a Ubuntu server 12.04 running kernel 3.5 RC2 (which includes Commit: 5aaa0b7a2ed5b12692c9ffb5222182bd558d3146)
With older kernels prior to commit c308b56b5398779cd3da0f62ab26b0453494c3d4, every data point in the above graph would be at a reported load average of 0.0
Idle enter / exit frequencies were selected to always add up to 180 hertz and also to avoid going below 25 hertz and avoid known alias frequencies.
This gave: 6 processes at 30 hz; 5 processes at 36 hz; 4 processes at 45 hz; 3 processes at 60 hz; 2 processes at 90 hz; and 1 process at 180 hz.
Note: This experiment includes changes and (hopefully) improvements from lessons learned from previous runs under other conditions.
First the main program was changed to include a command option to abort all processes when the first child process finishs. A significant time skew could develope between the processes and the actual load would trail off leading to a false sample when the last processes finally finished.
The order was reveresed from 6 to 1 processes to 1 to 6 processes, because the lower number of processes are the more informative in terms of magnitude of error in reported load averages (i.e. the experiment could be terminated sooner if the data was showing issues or no improvement).
To avoid discontinuities in the reported load averages, and to maintain predictable execution loop times in the main program, the cpu frequency governors were set to powersave mode.
The main program, as a text file.
The program, as a text file, that generates the script for execution conditions of the main program.
The resulting script, as a text file, edited for one hour (4 time constants of the 15 minute load average) of extra settling time between number of processes changes.
The raw data as a text file.
The oversampled data as a text file. (warning: large file ~ 1 megabyte)) Sometimes used to correct bad data or outlyer samples.
The main program parameters were selected to print an update every 10 seconds and to run for 30 minutes.
Obviously, the server can not be used for anything else during the execution of this test, or the reported load averages might be biased. See the background (idle) results which verifies that the background can be ignored.