Volker, not a full answer, but here is some static size stats:
Server x86_64 AArch64 regular 23M 20M lto 17M 14M Minimal x86_64 AArch64 regular 4.9M 3.9M lto 4.7M 3.6M -Aleksei On 15/01/2020 16:40, Volker Simonis wrote: > While we are speaking about all the drawbacks of LTO, it's still not > clear what the benefits are? In the very first mail Matthias mentioned > that there might be performance improvements but that performance is > not the main driving factor behind this initiative. So is it the > reduced code size (Matthias mentioned something around ~10%)? > > It would be nice to see some real numbers on various platform for > both, the performance improvements for native parts like JIT/GC as > well as for the size reduction. > > Aleksei Voitylov <aleksei.voity...@bell-sw.com > <mailto:aleksei.voity...@bell-sw.com>> schrieb am Di., 14. Jan. 2020, > 09:54: > > > On 14/01/2020 19:57, Baesken, Matthias wrote: > > Hello Magnus and Aleksei, thanks for the input . > > > > The times you provided really look like they make a big > difference at least for people often building minimal-vm . > > Guess I have to measure myself a bit (maybe the difference is > not that big on our linux s390x / ppc64(le) ) . > > > >> If the change to enable lto by default is proposed, what would > be the > >> recommended strategy for development? > >> > > Probably we should a) do not enable it by default but just > make sure it can be enabled easily and works for the minimal-vm > That would be welcome. I have high hopes to LTO the VM some time by > default, and the tendency observed is that the compiler time overhead > for GCC becomes smaller. At the same time there is no reason why > vendors > that invested in testing and can absorb the build time hit could > provide > binaries with LTO built VMs by passing an additional option flag. > > or b) take it easy to disable it for local development. > > > > Best regards, Matthias > > > > > > > >> Magnus, Matthias, > >> > >> for me, lto is a little heavyweight for development. x86_64 > build time > >> with gcc 7: > >> > >> Server 1m32.484s > >> Server+Minimal 1m42.166s > >> Server+Minimal (--with-jvm-features="link-time-opt") 5m29.422s > >> > >> If the change to enable lto by default is proposed, what would > be the > >> recommended strategy for development? > >> > >> For ARM32 Minimal, please keep in mind that it's not uncommon > to disable > >> LTO plugin in commodity ARM32 gcc compiler distributions, so > for some it > >> does not matter what settings we have in OpenJDK. I believe > there could > >> be other reasons for that on top of build time (bugs?). > >> >
