[dpdk-dev] [PATCH] mk: optimize directory dependencies
Bruce Richardson
bruce.richardson at intel.com
Tue Jan 24 13:15:06 CET 2017
On Tue, Jan 24, 2017 at 05:10:15PM +0530, Jerin Jacob wrote:
> 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 at 6wind.com>
>
> Tested both approach on ThunderX. This patch looks better
>
> Tested-by: Jerin Jacob <jerin.jacob at 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
>
I agree that Olivier's patch is faster. However, I think I prefer having
the library dependencies in the makefiles for the libs themselves rather
than up a level. Given that we are only looking at ~2second of a
difference here in your tests - assuming -j flag - what is the actual
build time differences? My suspicion is that after Ferruh's simpler
patch is applied, the config time becomes such a small part of the
build, that the extra benefits from Oliviers work is not worth the extra
complexity.
Regards,
/Bruce
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