Re: [PATCH v2 0/7] record and rework component dependencies

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Aug 02, 2024 at 06:18:26PM +0100, Ferruh Yigit wrote:
> On 8/2/2024 1:44 PM, Bruce Richardson wrote:
> > As part of the meson build, we can record the dependencies for each
> > component as we process it, logging them to a file. This file can be
> > used as input to a number of other scripts and tools, for example, to
> > graph the dependencies, or to allow higher-level build-config tools to
> > automatically enable component requirements, etc.
> > 
> > The first patch of this set generates the basic dependency tree. The
> > second patch does some processing of that dependency tree to identify
> > cases where dependencies are being unnecessarily specified. Reducing
> > these makes it easier to have readable dependency graphs in future,
> > without affecting the build.
> > 
> > The following 4 patches are based on the output of the second patch, and
> > greatly cut down the number of direct dependency links between
> > components. Even with the cut-down dependencies, the full dependency
> > graph is nigh-unreadable, so the final patch adds a new script to
> > generate dependency tree subgraphs, creating dot files for e.g. the
> > dependencies of a particular component, or a component class such as
> > mempool drivers.
> > 
> > Bruce Richardson (7):
> >   build: output a dependency log in build directory
> >   devtools: add script to flag unneeded dependencies
> >   build: remove kvargs from driver class dependencies
> >   build: reduce library dependencies
> >   build: reduce driver dependencies
> >   build: reduce app dependencies
> >   devtools: add script to generate DPDK dependency graphs
> >
> 
> Tested-by: Ferruh Yigit <ferruh.yigit@amd.com>
> 
> Thanks for the update, output is now easier to consume with the help of
> the 'devtools/draw-dependency-graphs.py' script.
> A detail but script is not actually drawing graph, but parsing .dot
> file, name is a little misleading.
> 
> 
> Also for the patches that are converting explicit dependency to implicit
> dependency, I can see the benefit for the meson and graph. But also
> there is a value of keeping explicit dependency, it was an easy way to
> document dependencies of component for developers.
> So, I am not really sure which one is better.
> 

Up till now we did not keep a fully dependency list for each component
because the configuration time with meson completely exploded due to really
slow deduplication of dependencies there. I haven't checked with recent
versions of meson, though, so the problem may no longer be there now. Right
now, we have "partial dependency lists" - neither full list of dependencies
of a component, nor a minimal set. These patches don't bring us fully to a
minimal set, but bring us closer. I honestly don't think we need to enforce
either case - so long as we have all dependencies either explicilty or via
recursive dependency, things are fine.

/Bruce