Ftrace Function Graph ARM

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Revision as of 11:45, 26 October 2009 by Tim Bird (Talk | contribs) (add Documentation section)

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This page holds information from Tim Bird's talk at Linux Symposium Montreal (July, 2009). Tim talked about patches against the 2.6.31-rc1 kernel tree for adding function graph tracing to the ARM architecture, for the Ftrace system.

Presentation

Here is the presentation from the Japan Linux Symposium (also given at ELC Europe, in Grenoble France)

Here is the presentation from the Canada Linux Symposium session:

Paper

Here is Tim's paper for the Canada Linux Symposium for this work:

Documentation

See the file Documentation/trace/func-duration.txt, after applying the patches.

(Or, if you applied the 2.6.31 patches, see the file Documentation/trace/func-graph.txt However, this version is deprecated.)

Patches

2.6.32-rc5 patches

To apply, extract the patches and the series file. If you have 'quilt', extract the file directly into the top level of the kernel source tree (the top directory is called 'patches'). Then do "quilt push -a".

If you don't have quilt, apply the patches manually, in the order specified in the 'series' file, with a command like: "patch -p1 <patches/foo.patch"

2.6.31-rc1 patches

The following patches were submitted to the kernel mailing list in early July 2009. There are patches against kernel version 2.6.31-rc1.

Tools

FDD

The 'fdd' tool is now incorporated into the patch set, and is located in the kernel scripts directory after applying the patches. See the documentation in the kernel tree for instructions for use.

FTD

To install:

* Download
* rename to 'ftd': mv Ftd.txt ftd
* make it executable: chmod a+x
* Put it on your path somewhere: sudo mv ftd /usr/local/bin

Further Work

Base on feeback from ftrace developers on the kernel mailing list, and from other developers at the tracing mini-summit, I started working on an updated duration tracer, using a different filtering approach. This work already looks very promising, but is not ready for release yet (as of July 24, 2009).

I will be reporting on this work at ELC Europe and the Japan Linux Symposium, so look for some updates to this page in October, 2009, if this stuff hasn't been mainlined by then. Or just send me an e-mail asking about the status.