Re: [PATCH] mk: optimize directory dependencies

On 1/23/2017 5:19 PM, Olivier Matz wrote:

Before this patch, the management of dependencies between directories
had several issues:

- the generation of .depdirs, done at configuration is slow: it can take
  more than one minute on some slow targets (usually ~10s on a standard
  PC).

- for instance, it is possible to expressed a dependency like:
  - app/foo depends on lib/librte_foo
  - and lib/librte_foo depends on app/bar
  But this won't work because the directories are traversed with a
  depth-first algorithm, so we have to choose between doing 'app' before
  or after 'lib'.

- the script depdirs-rule.sh is too complex.

- we cannot use "make -d" for debug, because the output of make is used for
  the generation of .depdirs.

This patch moves the DEPDIRS-* variables in the upper Makefile, making
the dependencies much easier to calculate. A DEPDIRS variable is still
used to process library dependencies in LDLIBS.

After this commit, "make config" is almost immediate.

Signed-off-by: Olivier Matz <redacted>

Hi Olivier,

It seems both have pros and cons,

Your patch pros,
- faster
- and simpler implementation.

cons,
- Need to update another Makefile in another level to update
dependencies of a library/driver.
- Root level dependencies hardcoded to a mk level makefile.
- removes depgraph target too, not sure how commonly used



Original implementation pros:
- self contained, it manages dependencies of library in same Makefile
- no hardcoded dependencies, all resolved dynamically

cons,
- relatively slower, but not too bad with -j make option.
- complex implementation


I would prefer my version, surprisingly J, but it is good to have
alternatives, and I don't have strong opinion against your patch.

Thanks,
ferruh