[Buildroot] [PATCH 06/13] docs/manual: add section about build time graphing

[Yann E. MORIN <yann.morin.1998@free.fr>]

Thomas, All,

On 2014-02-23 16:04 +0100, Thomas Petazzoni spake thusly:
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> ---
>  docs/manual/common-usage.txt | 47 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 47 insertions(+)
> 
> diff --git a/docs/manual/common-usage.txt b/docs/manual/common-usage.txt
> index bef42c6..76e4023 100644
> --- a/docs/manual/common-usage.txt
> +++ b/docs/manual/common-usage.txt
> @@ -201,3 +201,50 @@ supported.
>  --------------------------------
>  GRAPH_OUT=svg make graph-depends
>  --------------------------------
> +
> +Graphing the build duration
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +[[graph-duration]]
> +
> +When the build of a system takes a long time, it is sometimes useful
> +to be able to understand which packages are the longest to build, to
> +see if anything can be done to speed up the build. In order to help
> +such build time analysis, Buildroot collects the build time of each
> +step of each package, and allows to generate graphs from these data.
> +
> +To generate the build time graph after a build, run:
> +
> +----------------
> +make graph-build
> +----------------
> +
> +This will generate a set of files in +output/graphs+ :
> +
> +* +build.hist-build.pdf+, an histogram of the build time for each
> +  package, ordered in the build order.
> +
> +* +build.hist-duration.pdf+, an histogram of the build time for each
> +  package, ordered by duration (longest first)
> +
> +* +build.hist-name.pdf+, an histogram of the build time for each
> +  package, order by package name.
> +
> +* +build.pie-packages.pdf+, a pie chart of the build time per package
> +
> +* +build.pie-steps.pdf+, a pie chart of the global time spent in each
> +  step of the packages build process.
> +
> +This +graph-build+ target requires the Python Matplotlib and Numpy
> +libraries to be installed (+python-matplotlib+ and +python-numpy+ on
> +most distributions), and also the +argparse+ module if you're using a
> +Python version older than 2.7 (+python-argparse+ on most
> +distributions).
> +
> +By default, the output format for the graph is PDF, but a different
> +format can be selected using the +GRAPH_OUT+ environment variable. The
> +only other format supported is PNG:
> +
> +----------------
> +GRAPH_OUT=png make graph-build
> +----------------

We also have GRAPH_ALT which sets an alternative colour-scheme for the
time graphs:
    GRAPH_ALT=y make graph-build

Which can be combined with GRAPH_OUT, of course.

Regards,
Yann E. MORIN.

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