clear

Clears the values from an aggregation while retaining aggregation keys.

void clear(@ aggr)

The clear function takes an aggregation as its only parameter. The clear function clears only the aggregation's values, while the aggregation's keys are retained. If the key is referenced after the clear function is run, it has a zero value.

Example 8-5 How to use clear to show the system call rate only for the most recent ten-second period

The clear function is used inside the tick-10sec probe to clear the counter values inside the @func aggregation.

#pragma D option quiet

BEGIN
{
  last = timestamp;
}

syscall:::entry
{
  @func[execname] = count();
}

tick-10sec
{
  normalize(@func, (timestamp - last) / 1000000000);
  printa(@func);
  clear(@func);
  last = timestamp;
}