> (btw I wonder how much effect profile guided optimization would bring in your experiments )
That's good idea; I'm also curious about PGO. I know some apps get 10-20% performance boost, however setting up PGO is pretty inconvenient. But maybe having it run over the DaCapo / Renaissance benchmarks would make a good profile. I also used some flags that OpenJDK could pickup, like `-fomit-frame-pointer` on non-debug builds. I also haven't had any problems running with the higher optimization, Ofast. > What alternatives do you have in mind? There are many opportunities I think. One way would be to allow jar / jmod files to use a modern compression algorithm (like LZ4). Not only would distributions be smaller but probably faster as well, since the cost of IO >> decompression in many cases. The size of OpenJDK's jar/jmod files is much larger than libjvm.so. And this isn't my idea, I saw it on Aleksey Shiplev's twitter some time ago: https://twitter.com/shipilev/status/1100396679285665794 On Wed, Dec 18, 2019 at 10:07 AM Baesken, Matthias <matthias.baes...@sap.com> wrote: > > > - I compiled with clang since I'm on Mac. > - > > > > Thanks for clarifying, that’s what I thought . > > > > (btw I wonder how much effect profile guided optimization would bring in > your experiments ) > > > > > > - My opinion is that there are probably more compelling alternatives > if reducing binary size is the goal. Even if the tests show that Os/O2 is > no different than O3, > - who knows if this will be true in the future. > - > > > > What alternatives do you have in mind ? > > > > Best regards, Matthias > > > > > > *From:* August Nagro <augustna...@gmail.com> > *Sent:* Mittwoch, 18. Dezember 2019 14:42 > *To:* Baesken, Matthias <matthias.baes...@sap.com> > *Cc:* claes.redes...@oracle.com; Doerr, Martin <martin.do...@sap.com>; > erik.joels...@oracle.com; build-dev@openjdk.java.net; > hotspot-...@openjdk.java.net > *Subject:* Re: RE: building libjvm with -Os for space optimization - was > : RE: RFR: 8234525: enable link-time section-gc for linux s390x to remove > unused code > > > > I compiled with clang since I'm on Mac. > > > > The Renaissance benchmark suite is also a good one that I learned about > recently. > > > > My opinion is that there are probably more compelling alternatives if > reducing binary size is the goal. Even if the tests show that Os/O2 is no > different than O3, who knows if this will be true in the future. > > > > Regards, > > > > - August > > > > On Wed, Dec 18, 2019, 1:58 AM Baesken, Matthias <matthias.baes...@sap.com> > wrote: > > Hi August , thanks for pointing to your webpage, very interesting ! > > We did our builds+tests/benchmarks with gcc 7.4.0 , what > compiler+version did you use? > > Probably I should look a bit more into Dacapo (we used that one in the > past too sometimes). > > Best regards, Matthias > > > > > > I published some benchmarks of OpenJDK on Mac with Ofast and O3 [1]. > > Some microbenchmarks like Netty’s HttpObjectEncoder experienced >100% > > speedup with O3, and the more real-world Dacapo suite was ~15% > > improvement over O2 (which is exactly the same as Os). I did include a > few > > other flags, however the speedup was primarily due to optimization level. > > > > Building with Os is the old wisdom. It used to be the case that many > programs > > would be faster with the smaller binary size, but this is almost never > the case > > nowadays. > > > > - August > > > > [1]: http://august.nagro.us/optimized-openjdk.html > >
