Choosing a Value For the Profiling Interval

See Also

Selecting an appropriate profiling interval is a balance between obtaining good statistics and minimizing the distortion of the performance of your program. The default Normal interval of 10 ms was selected to keep the distortion below about 5%.

The rate at which data is collected is inversely proportional to the profiling interval. If the experiment becomes too large you can increase the profiling interval to reduce the amount of data collected, but the statistical quality of the data is reduced.

The profiling interval is restricted to a multiple of the system clock resolution. If the interval you choose is not a multiple of the system clock resolution, then one of the following actions takes place.

The default system clock resolution is 10 milliseconds. If you want to do profiling at higher resolution, you can change the system clock rate to give a resolution of 1 millisecond. To do this you must have root privilege.

To specify a system clock rate of 1 millisecond:

  1. Add the line set hires_tick=1 to the file /etc/system.
  2. Reboot your system.

See the Solaris Tunable Parameters Reference Manual for more information.

See also
Collecting Performance Data
Clock Data
Estimating the Experiment Size
Controlling the Experiment Size

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