Messages in this thread | | | Date | Wed, 9 Dec 2009 14:40:19 -0800 | From | Tim Bird <> | Subject | [PATCH 0/4] ftrace - Add function duration tracer to ftrace |
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I've created a new tracer, called the "function duration" tracer, which is derived from the existing function graph tracer. The new feature of this tracer, relative to the function graph tracer, is that it allows filtering by duration.
The rationale for creating a separate tracer is that some of the optimizations used for the duration tracer were incompatible with the function graph tracer. Specifically, I avoid superfluous calls to the ring_buffer code, avoiding substantial overhead penalties. Also, this tracer is more suitable for use at bootup time (I have a set of patches pending which adds support for that, on ARM).
The output format for the tracer is amenable to grep-ing. That is, the duration is on the same line as the function name.
For details about this, see my presentation from the Japan Linux Symposium: http://elinux.org/images/7/70/Measuring-function-duration-with-ftrace-oct-2009.pdf
with more information available at the elinux wiki page: http://elinux.org/Ftrace_Function_Graph_ARM
Patches to follow. Thanks. -- Tim
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