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.ja...@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
