Why systemtap loses events and what can be done about it?

[Frank Ch. Eigler]

Brad Peters <bpeters@linux.vnet.ibm.com> writes:

> [...] as interrupts are disabled whenever a probe is run, only one can run
> at any given time on a per cpu basis. [...]

We would also block reentrant probes, so disabling interrupts is only
a means rather than the cause of atomic probe execution.

> The only solution, AFIK, is to optimize/minimize your probe code.

Running it with "-t" (timing) will give some measurements about how
much time the probe handlers are taking, and thus can help guide
optimization.

> This does not eliminate the problem, however.  Given enough probe
> hits, you will still see contention.

Yes, that is the nature of the beast.

- FChE