Tasker Power

Upon startup, the vovtasker computes the raw power of the CPU on the current host by timing a known test routine consisting of a balanced mix of integer, double and string operations. The power is inversely proportional to the time it takes to execute the test routine.

To maintain the efficiency of the vovserver for other tasks (such as scheduling), only the 2 most significant digits of the calculations are used to search for and identify the fastest tasker host.

Here is a sample output of the startup phase of a tasker, which shows the results of the power measurements:

% vovtasker -N
vovtasker Jan 27 17:49:03 
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        Sun5/5.2 Jan  5 2000 08:28:50
        evcdrom@mercury
vovtasker Date Stamp: Thu Jan 27 17:49:04 2000
vovtasker Jan 27 17:49:04 Test 1: INTEGER OPS  W=  1.00 Reps= 500 T=  16.95ms
vovtasker Jan 27 17:49:04 Test 1: DOUBLE  OPS  W=  1.00 Reps=  25 T=  73.64ms
vovtasker Jan 27 17:49:04 Test 1: CHAR    OPS  W=  0.10 Reps=  10 T=  74.12ms
vovtasker Jan 27 17:49:04 ---- Weighted time: 98.01ms
vovtasker Jan 27 17:49:04 Test 2: INTEGER OPS  W=  1.00 Reps= 500 T=  17.45ms
vovtasker Jan 27 17:49:04 Test 2: DOUBLE  OPS  W=  1.00 Reps=  25 T=  73.36ms
vovtasker Jan 27 17:49:04 Test 2: CHAR    OPS  W=  0.10 Reps=  10 T=  74.68ms
vovtasker Jan 27 17:49:04 ---- Weighted time: 98.27ms
vovtasker Jan 27 17:49:04 Test 3: INTEGER OPS  W=  1.00 Reps= 500 T=  17.52ms
vovtasker Jan 27 17:49:04 Test 3: DOUBLE  OPS  W=  1.00 Reps=  25 T=  73.52ms
vovtasker Jan 27 17:49:04 Test 3: CHAR    OPS  W=  0.10 Reps=  10 T=  72.15ms
vovtasker Jan 27 17:49:04 ---- Weighted time: 98.26ms
vovtasker Jan 27 17:49:04 Best weighted time: 98.01ms

This method is very effective in discriminating among CPUs with the same architecture, such as all Sparcs. If you are running on a heterogeneous network, you will notice that the test routine executes very well on PowerPCs and x86 processors compared to Sparc processors. To compensate this effect, we recommended setting the tasker coefficient on PowerPCs and x86 hosts to a value greater than 1.0 (e.g. 2.0).

On a multiprocessor machine, "raw power" refers to the power of each single CPU.

The current power of a machine takes into account both the raw power and the load (as computed by the UNIX utility uptime). On a multiprocessor, if the load is less than the number of CPUs minus one, the current power is the same as the raw power, because there is a processor that is practically idle.

The effective power takes into account the "self load" created by the jobs that have been initiated by the tasker itself.