I have submitted https://reviews.freebsd.org/D23376 for avoiding the PowerMac threads-stuck-sleeping issue

[Francis Little]

Well that seems to do the trick!

PowerMac G5 Quad, running the r357172 kernel, plus this patch.

All fans normal, no odd hanging threads, compiling ports etc with all 4
cores, seems stable.

Will continue testing.


On Sun, 26 Jan 2020 at 23:28, Mark Millard via freebsd-ppc <
freebsd-ppc at freebsd.org> wrote:

> I've described my first ever reviews.freebsd.org/D?????
> submittal with:
>
> QUOTE
> REVISION SUMMARY
>  Explicitly initialize the bsp's TB value early on. For PowerMacs with
> multiple sockets or cores only, have machdep_ap_bootstrap for each ap make
> a round trip with the bsp to get a current bsp's TB value and then shift
> the ap's time so that the midpoint of the shifted round tip interval
> approximately matches the TB value the bsp supplied. The round trips and
> data transfers use a memory protocol.
>
>  For non-PowerMacs, do the old way for the ap's.
>
> TEST PLAN
>  I've been running based on the patches being invovled since late 2019-May
> or so: PowerMac11,2 with 2 sockets, 2 cores each, and PowerMac3,6 with 2
> sockets, 1 core each. No examples of 1 socket with 2 cores, unfortunately.
> No examples of powerpc64 or powerpc non-PowerMacs either. I do use the same
> source tree to build for amd64, aarch64, and armv7 and they have been
> working too. But the patch material is extracted from a source tree that
> has more local changes: the testing has not been with only these changes.
>
>  I've not had any examples of the stuck-sleeping issue since adopting
> these changes. Nor have I had new problems from the changes.
> END QUOTE
>
>
> A summary of my changes is:
>
>
> Part 0:
> Avoid interrupts messing up mttb use:
>
> sys/powerpc/include/cpufunc.h
>
>
> Part 1:
> Enable the "alternate_timebase_sync_style" indicator
> only for PowerMacs:
>
> sys/powerpc/powermac/platform_powermac.c
>
>
> Part 2:
> The code supporting machdep_ap_bootstrap's part of the
> hard work, including the changes to machdep_ap_bootstrap:
>
> sys/powerpc/powerpc/mp_machdep.c
>
>
> Part 3:
> Making sure that the bsp follows the rule:
> "The TB is a volatile resource and must be initialized during reset."
>
> sys/powerpc/powerpc/machdep.c
>
>
>
>
> I'll note that I'm not style(9) literate/familiar and at the time
> my capacity went to investigating the problem and potential solutions,
> not to style(9). So, once a technique is classified as okay, how
> it is written in the source would need its own round of work,
> presuming my submittal does not inspire a separate fix by someone.
>
> ===
> Mark Millard
> marklmi at yahoo.com
> ( dsl-only.net went
> away in early 2018-Mar)
>
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