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Oracle Solaris 11.1 Dynamic Tracing Guide     Oracle Solaris 11.1 Information Library
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Document Information


1.  About DTrace

2.  D Programming Language

3.  Aggregations

Aggregating Functions


Printing Aggregations

Data Normalization

Clearing Aggregations

Truncating aggregations

Minimizing Drops

4.  Actions and Subroutines

5.  Buffers and Buffering

6.  Output Formatting

7.  Speculative Tracing

8.  dtrace(1M) Utility

9.  Scripting

10.  Options and Tunables

11.  Providers

12.  User Process Tracing

13.  Statically Defined Tracing for User Applications

14.  Security

15.  Anonymous Tracing

16.  Postmortem Tracing

17.  Performance Considerations

18.  Stability

19.  Translators

20.  Versioning


Clearing Aggregations

When using DTrace to build simple monitoring scripts, you can periodically clear the values in an aggregation using the clear function. This function takes an aggregation as its only parameter. The clear function clears only the aggregation's values; the aggregation's keys are retained. Therefore, the presence of a key in an aggregation that has an associated value of zero indicates that the key had a non-zero value that was subsequently set to zero as part of a clear. To discard both an aggregation's values and its keys, use the trunc. See Truncating aggregations for details.

The following example adds clear to Example 3-1:

Example 3-2 Clearing Aggregations

#pragma D option quiet

        last = timestamp;

        @func[execname] = count();

        normalize(@func, (timestamp - last) / 1000000000);
        last = timestamp;

While Example 3-1 shows the system call rate over the lifetime of the dtrace invocation, the preceding example shows the system call rate only for the most recent ten-second period.