[dpdk-dev] [PATCH] mk: optimize directory dependencies
Bruce Richardson
bruce.richardson at intel.com
Tue Jan 24 12:26:33 CET 2017
On Tue, Jan 24, 2017 at 12:19:49PM +0100, Robin Jarry wrote:
> Hi Olivier,
>
> 2017-01-23, Olivier Matz:
> > 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).
>
> Indeed, on a Qualcomm development board where disk I/O is quite slow:
>
> $ git describe
> v17.02-rc1-3-g61207d014fc9
>
> $ time make config T=arm64-armv8a-linuxapp-gcc
> real 1m4.308s
>
Wow, what is the build time in that case?
> > - for instance, it is possible to expressed a dependency like:
>
> s/expressed/express/
>
> > - we cannot use "make -d" for debug, because the output of make is used
> > for the generation of .depdirs.
>
> That is really annoying when debugging makefiles.
>
> After applying this patch:
>
> $ git am mk-optimize-directory-dependencies.patch
> Applying: mk: optimize directory dependencies
> $ rm -rf build/
>
> $ time make config T=arm64-armv8a-linuxapp-gcc
> real 0m0.111s
>
> Almost 600 times faster than before!
>
> I prefer this solution to the one proposed by Ferruh (which is interesting
> but requires to run parallel make). Here is a test with the other patch:
>
> $ git am mk-parallelize-make-config.patch
> Applying: mk: parallelize make config
> $ rm -rf build/
> $ grep -c processor /proc/cpuinfo
> 24
>
> $ time make config T=arm64-armv8a-linuxapp-gcc -j24
> real 0m11.253s
>
> Here only 6 times faster than before, even when using 24 parallel processes.
>
> Tested-by: Robin Jarry <robin.jarry at 6wind.com>
Hi Robin,
what are the differences in the patches like when doing a build rather
than just a config? If the build is minutes long because of slow IO,
is the extra 10 seconds really going to make that much of a difference?
Regards,
/Bruce
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