On Thu, Jan 7, 2021 at 3:24 PM Neal Gompa <ngompa13(a)gmail.com> wrote:
On Thu, Jan 7, 2021 at 10:10 AM Daniel Pocock <daniel(a)pocock.pro> wrote:
> On 07/01/2021 12:35, Dan Horák wrote:
> > Hi Daniel,
> > On Wed, 6 Jan 2021 14:11:37 +0100
> > Daniel Pocock <daniel(a)pocock.pro> wrote:
> >> We did some more troubleshooting of AMD Radeon issues on ppc64
> >> As with Nouveau, it looks like a change from 64k to 4k page size got it
> >> working again with RX 5700. I suspect it will be similar for RX 6800 if
> >> we can get some of them, they are a good complement for the compute power.
> >> The issue is page size, not ppc64
> > are you talking about Maurizio's issue? When I was talking with the guy
> > who fixed the Navi 10 driver for Power, he wasn't aware of any page
> > size issues. But it sounds plausible.
> Yes, it is in the Raptor forum
> To save reading, I gave him the following in an apt repository:
> - 5.9.6 kernel with 4k page size
> - mesa 20.3
> - deps for mesa (llvm-11, libdrm, ...)
> He took the 2020-10-22 firmware snapshot from Debian unstable
> He disabled Wayland, to use Xorg
> It worked.
> I'm hoping that exactly the same set of packages will work for me
> whenever I can get my hands on an RX 6800 XT card.
> As mentioned elsewhere in this thread and in various parts of the Raptor
> forum, especially this thread, there are a range of applications
> where page size appears to have some impact.
> I'd like to emphasize that there are a range of issues where page size
> does not appear to be a factor, there are a backlog of these issues.
> Therefore, emphasizing this quite strongly, I feel it is better for
> people to run 4k page size on workstations from F-34 so we can clearly
> flush out the PPC issues on 4k before we even begin to address issues
> with 64k. As examples, I have issues with Blender, Firefox and
> JPEGs in OBS where page size has been eliminated but I also have
> another issue with Firefox, or maybe v4l2-loopback, where page size
> is a factor.
> Vikings and Raptor hope to sell a lot more of these systems when they go
> live in 2021. Vikings in particular has put great effort into a
> German-engineering water cooling solution, there is a leaked photo in
> the Raptor forum. Personally, I already identified the traps in this
> platform within hours of unboxing but I know a lot of the users,
> including Fedora users, will benefit from a slightly softer landing on
> POWER9. I can't personally spend time following every issue through to
> completion myself (unless somebody wants to offer me a bounty) but I try
> to document them as well as I can both here and in the bug trackers.
You could make a Change proposal to switch Fedora on POWER back to 4k
page sizes. Or just talk to the Fedora kernel maintainers about
switching it back. We did this four years ago for ARM (as Peter
noted), and if it really continues to be a problem for desktop
POWER systems, then switching back makes sense.
The arm team made that change by engaging with all the people that
would be impacted after working with the toolchain teams to ensure the
userspace had all the needed fixes to ensure it was purely a kernel
config change, that was around 18 months work to get to that point
(yes, and POWER64 likely benefits from that ~ 10 releases later) but
the likes of IBM should be engaged because they obviously also have an
interest and are active users/contributors of Fedora on POWER.