Set the overhead for tracing system calls

-O option is used to set the overhead for tracing system calls, and the unit is microseconds (us). The following is excerpted from manual:

This is useful for overriding the default heuristic for guessing how much time is spent in mere measuring when timing system calls using the -c option. The accuracy of the heuristic can be gauged by timing a given program run without tracing (using time(1)) and comparing the accumulated system call time to the total produced using -c.

Check the source code:

    ......
    ts_mul(&dtv, &overhead, counts[i].calls);
    ts_sub(&counts[i].time, &counts[i].time, &dtv);
    ......

The overhead time is subtracted from the total consuming time, and this option just makes sure the measure of time spent on system calls to be more accurate.

results matching ""

    No results matching ""