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Oracle Solaris Dynamic Tracing Guide     Oracle Solaris 11 Information Library
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Document Information


1.  About DTrace

2.  D Programming Language

3.  Aggregations

4.  Actions and Subroutines

5.  Buffers and Buffering

Principal Buffers

Principal Buffer Policies

switch Policy

fill Policy

fill Policy and END Probes

ring Policy

Other Buffers

Buffer Sizes

Buffer Resizing Policy

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

Buffer Resizing Policy

Occasionally, the system might not have adequate free kernel memory to allocate a buffer of desired size either because not enough memory is available or because the DTrace consumer has exceeded one of the tunable limits described in Chapter 10, Options and Tunables. You can configure the policy for buffer allocation failure using bufresize option, which defaults to auto. Under the auto buffer resize policy, the size of a buffer is halved until a successful allocation occurs. dtrace(1M) generates a message if a buffer as allocated is smaller than the requested size:

# dtrace -P syscall -b 4g
dtrace: description 'syscall' matched 430 probes
dtrace: buffer size lowered to 128m


# dtrace -P syscall'{@a[probefunc] = count()}' -x aggsize=1g
dtrace: description 'syscall' matched 430 probes
dtrace: aggregation size lowered to 128m

Alternatively, you can require manual intervention after buffer allocation failure by setting bufresize to manual. Under this policy, a failure to allocate will cause DTrace to fail to start:

# dtrace -P syscall -x bufsize=1g -x bufresize=manual
dtrace: description 'syscall' matched 430 probes
dtrace: could not enable tracing: Not enough space

The buffer resizing policy of all buffers, principal, speculative and aggregation, is dictated by the bufresize option.