[Openmp-dev] Build is terribly slow on Arm

[Itaru Kitayama via Openmp-dev]

Also as I’m using local SSD, I suspect it’s due to something with
offloading options at this moment.

On Wed, Jun 10, 2020 at 19:03 Itaru Kitayama <itaru.kitayama at gmail.com>
wrote:

> Sorry I take it back then. An X86 build finishes just a few minutes, while
> on AArch64 takes a half hour, thus I’m wondering.
>
> AArch64 LLVM build is much faster when no offloading stuff is explicitly
> set at CMake configuration time.
>
> On Wed, Jun 10, 2020 at 18:54 Jonas Hahnfeld <hahnjo at hahnjo.de> wrote:
>
>> You wrote "They were both Debug build". Maybe I misunderstand?
>>
>> Am Mittwoch, den 10.06.2020, 18:52 +0900 schrieb Itaru Kitayama:
>> > Why do you think I build in Debug? I try to
>> > avoid that all time.
>> >
>> > On Wed, Jun 10, 2020 at 18:38 Jonas Hahnfeld <hahnjo at hahnjo.de> wrote:
>> > > You should not use Debug build to compare the performance of
>> compilers.
>> > > As you're targeting different architectures, you might run into
>> > > different checks in the two backends. I believe it's possible this is
>> > > triggered by OpenMP code generation which might hit some corner cases.
>> > > This could also happen in Release builds, but might be less probable.
>> > >
>> > > Also keep in mind that AArch64 (which you're probably talking about in
>> > > the context of HPC) now uses GlobalISel in some configurations. I
>> don't
>> > > remember if it's with or without optimizations (or maybe even both
>> > > nowadays?), but you can try to deactivate this on the command line to
>> > > rule out this area.
>> > >
>> > > Regards
>> > > Jonas
>> > >
>> > > Am Dienstag, den 09.06.2020, 08:12 +0900 schrieb Itaru Kitayama via
>> > > Openmp-dev:
>> > > > They were both Debug build, but it took 20-25 minutes to finish on
>> Arm.
>> > > >
>> > > > On Tue, Jun 9, 2020 at 7:50 AM Itaru Kitayama <
>> > > > itaru.kitayama at gmail.com
>> > > > > wrote:
>> > > > > My OpenMP offloading app builds within a minute or so on
>> > > > > x86, but the same app takes longer than 5 minutes on Arm.
>> > > > > How do I investigate this further, supplying -v and post
>> > > > > the log here?
>> >
>> >
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/openmp-dev/attachments/20200610/b5e43e48/attachment-0001.html>