15.1 Limit Enabled Probes

Dynamic instrumentation techniques enable DTrace to provide unparalleled tracing coverage of the kernel and of arbitrary user processes. While this coverage allows revolutionary new insight into system behavior, it also can cause enormous probe effect. If tens of thousands or hundreds of thousands of probes are enabled, the effect on the system can easily be substantial. Therefore, you should only enable as many probes as you need to solve a problem. For example, you should not enable all syscall probes if a more concise enabling will answer your question. Your question might allow you to concentrate on a specific module of interest or a specific function.

DTrace can also be used in situations where large numbers of probes must be enabled for a question to be answered. Enabling a large number of probes might slow down the system quite a bit, but it never induces fatal failure on the machine. You should therefore not hesitate to enable many probes if required.