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Re: resolving probe point context_switch
- From: fche at redhat dot com (Frank Ch. Eigler)
- To: "Jason Yeh" <jason dot yeh at amd dot com>
- Cc: systemtap at sources dot redhat dot com
- Date: 12 Oct 2006 16:10:53 -0400
- Subject: Re: resolving probe point context_switch
- References: <20061012152411.GA3979@redhat.com> <452E8704.1020105@amd.com>
"Jason Yeh" <jason.yeh@amd.com> writes:
> [...] I have been trying to get Systemtap to place probe in the
> scheduler and hoping to experiment using Systemtap to emulate
> certain behavior of Perfmon2 similar to what Frank mentioned in the
> email titled "Model-Specific Register".
Thanks for giving that a try!
> [...]
> while: resolving probe point kernel.inline("context_switch")
> while: resolving probe point kernel.inline("finish_task_switch")
> while: resolving probe point kernel.inline("pull_task")
> while: resolving probe point kernel.inline("idle_balance")
We have some known weaknesses probing inline functions, which we may
be able to improve significantly. In the mean time, something coarser
might have to do:
probe kernel.statement("schedule") { /* leaving tid() on cpu() */ }
probe kernel.function("schedule").return { /* resuming tid() on cpu() */ }
FWIW, the scheduler is one of the spots that would benefit most from
static instrumentation markers.
- FChE