On Tue, Jul 3, 2018 at 12:15 AM Erwan Velu <evelu@xxxxxxxxxx> wrote: > > An update status on this. > > I forgot to mention some needed ccache configuration : > - ccache -o sloppiness=time_macros > - ccache -o run_second_cpp=true > > I'll will push a new PR to handle this. > > The first builds passed with it set manually on a build node with excellent results ! > > A make check job is now passing in 14mn instead of 55mn ! > Awesome! i was wondering why it still took 56 mins after pushing your change to jenkins. =) > > ----- Mail original ----- > De: "Erwan Velu" <evelu@xxxxxxxxxx> > À: "Ceph Development" <ceph-devel@xxxxxxxxxxxxxxx> > Envoyé: Jeudi 28 Juin 2018 19:04:42 > Objet: Re: Improving the build performance > > After a review with Kefu, it appear the BUILD_DATE is perfectly useless here. > > So only this part is necessary to get the ccache working better: > > export SOURCE_DATE_EPOCH=$(date +%D |date -f- +%s); > > ----- Mail original ----- > De: "John Spray" <jspray@xxxxxxxxxx> > À: "Erwan Velu" <evelu@xxxxxxxxxx> > Cc: "Ceph Development" <ceph-devel@xxxxxxxxxxxxxxx> > Envoyé: Jeudi 28 Juin 2018 16:12:44 > Objet: Re: Improving the build performance > > On Thu, Jun 28, 2018 at 3:03 PM Erwan Velu <evelu@xxxxxxxxxx> wrote: > > > > Hi Folks, > > > > I've been wondering why the ccache was that inefficient on the CI. > > It appear and that is confirmed by local builds that two consecutives builds of the exact same code leads to < 1% of cache hit. > > This is actually a very bad cache performance : As the cache hit is very low, the needed time to create the cache is not compensated, leading to a 10% loss of performance regarding a build without ccache. > > > > C and C++ are usually providing much better results. > > This kind of misses in the cache are usually tied to some little variations introduced at compilation times like a sha1 or a timestamp (__DATE__ or __TIME__ or similar). > > Thanks to the wonderful project from debian to get reproducible builds (https://wiki.debian.org/ReproducibleBuilds) it is possible to enforce a particular setup at build time (https://wiki.debian.org/ReproducibleBuilds/TimestampsProposal). > > > > I've been trying that on my testing host with a very nice result: > > - before, make takes 33mn with -j 24 (the user time is reported to 630mn). > > - after , make takes 7mn with -j 24 (the user time is reported to 77mn) > > Wow, that's huge! Nice work! > > John > > > > > This is a nearly a 5x speedup on the whole process which includes non cachable stuff like linking or npm stuff. > > > > To achieve that, I've been setting up SOURCE_DATE_EPOCH & BUILD_DATE like : > > export SOURCE_DATE_EPOCH=$(date +%D |date -f- +%s); > > export BUILD_DATE=$(date --utc --date=@${SOURCE_DATE_EPOCH} +%Y-%m-%d) > > > > In this example, the SOURCE_DATE_EPOCH is the current day. Unless this variable is redefined, the same source code will hit the cache. > > This example is taken from a PR for the CI (https://github.com/ceph/ceph-build/pull/1058) where I wanted to get a cache being valid only for a day. > > > > Note that if the Ceph code is changing too much, the cache have to be partially or totally repopulated. From the tests I run, it usually goes between 0 & 50% of speedup in such case. > > To increase the cache efficiency, some could want to call do_cmake with ARGS='-D ENABLE_GIT_VERSION=OFF' to avoid having the git hash in the ceph_ver header. > > > > These two little changes improves significantly the local build time and will do soonish also on the CI (https://github.com/ceph/ceph-build/pull/1058) where I expect a great speedup ! > > > > Erwan, > > -- > > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Regards Kefu Chai -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
