Comment # 5 on bug 1200487 from Mel Gorman

(In reply to Jiri Slaby from comment #3)
> (In reply to Mel Gorman from comment #2)
> > (In reply to Jiri Slaby from comment #1)
> > > Just a note: it's still pretty fragile. So if it crashes, just please let me
> > > know your setup and the crash. I'll try to fix it up.
> > 
> > Are there any toolchain support changes or is SLE 15 SP4 userspace suitable?
> 
> I am not sure if you mean for building or running.
> 

Both, can it be built and booted from a stable userspace (e.g. SLE 15 SP4)?

> Building:
> lto is supported for a long time in gcc, so gcc-7 (and the rest of the
> 15sp4's toolchain) should be fine. But noone tried, so I would expect
> glitches.
> 
> Running:
> It won't run there as it is currently built (i.e. against Tumbleweed). But
> it's quite easy to fix the IBS projects to build against backports, so that
> it runs on 15sp4 just fine.
> 
> > Are there kernel.org branches should LTO enabled vs disabled?
> 
> Sorry, I don't understand what you are asking here. Do you want me to push
> an upstream kernel w/ and w/o LTO patches to git.kernel.org?
> 

I don't blame you, my question made no sense. I meant -- are there
kernel-source.git branches with any modifications necessary made? That way, I
could use the minimal SLE patches against mainline as the baseline, then LTO
disabled, then LTO enabled.

> > Factory as userspace would be problematic as it keeps changing and has
> > limited to no remote deployment support currently available. I also need to
> > have an idea of what patches are applied just to make LTO an option because
> > the real comparison should not be between LTO enabled vs disabled but
> > between vanilla mainline vs LTO-disabled vs LTO-enabled. Given that it is
> > expected to be fragile and likely break, it'll be only queued against one
> > machine as a starting point.
> 
> OK, the project setup allows for an easy diff -- it's linked against
> Kernel:stable. So the patches (and a config diff) are these:
> https://build.suse.de/package/rdiff/home:jirislaby:kernel-lto/kernel-
> source?opackage=kernel-source&oproject=Devel%3AKernel%3Astable
> 
> Or you can download patches.addon.tar.bz2 from home:jirislaby:kernel-lto
> directly:
> https://build.suse.de/source/home:jirislaby:kernel-lto/kernel-source/patches.
> addon.tar.bz2
> 

I can do this if a branch is not available. The only concern would be that the
baseline is against a different commit and I want to reduce as many variables
as possible.

I can add the gcc-12 repo no problem but I want to ensure that each of the
three kernels (baseline, LTO disabled, LTO enabled) are definitely built from
the same toolchain. I can use the rpms but it is not preferred.