Re: [PATCH] mk: optimize directory dependencies

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

On Mon, Jan 23, 2017 at 06:19:13PM +0100, 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 <olivier.matz@6wind.com>

Tested both approach on ThunderX. This patch looks better

Tested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>

➜ [master]GB-2S [dpdk-master] $ time make config T=arm64-thunderx-linuxapp-gcc 
Configuration done

real    0m18.112s
user    0m2.810s
sys     0m0.660s

➜ [master]GB-2S [dpdk-master] $ pwclient git-am 19859
Applying patch #19859 using 'git am'
Description: [dpdk-dev] mk: parallelize make config
Applying: mk: parallelize make config

➜ [master]GB-2S [dpdk-master] $ rm -rf build
➜ [master]GB-2S [dpdk-master] $ time make config T=arm64-thunderx-linuxapp-gcc -j 8
Configuration done

real    0m2.812s
user    0m3.020s
sys     0m0.870s

➜ [master]GB-2S [dpdk-master] $ rm -rf build
➜ [master]GB-2S [dpdk-master] $ time make config T=arm64-thunderx-linuxapp-gcc -j 16
Configuration done

real    0m1.748s
user    0m3.040s
sys     0m1.020s

➜ [master]GB-2S [dpdk-master] $ rm -rf build
➜ [master]GB-2S [dpdk-master] $ time make config T=arm64-thunderx-linuxapp-gcc -j 32
Configuration done

real    0m1.422s
user    0m3.380s
sys     0m1.080s

➜ [master]GB-2S [dpdk-master] $ pwclient git-am 19918
Applying patch #19918 using 'git am'
Description: [dpdk-dev] mk: optimize directory dependencies
Applying: mk: optimize directory dependencies

➜ [master]GB-2S [dpdk-master] $ rm -rf build
➜ [master]GB-2S [dpdk-master] $ time make config T=arm64-thunderx-linuxapp-gcc 
Configuration done

real    0m0.064s
user    0m0.000s
sys     0m0.000s
➜ [master]GB-2S [dpdk-master] $ rm -rf build
➜ [master]GB-2S [dpdk-master] $ time make config T=arm64-thunderx-linuxapp-gcc -j 8
Configuration done

real    0m0.055s
user    0m0.000s
sys     0m0.000s