On Tue, 2018-05-22 at 08:50 +0200, Sebastian Andrzej Siewior wrote: > > Regarding the preempt_disable() in the original patch in uv_read_rtc(): > This looks essential for PREEMPT configs. Is it possible to get this > tested by someone or else get rid of the UV code? It looks broken for > "uv_get_min_hub_revision_id() != 1".
I suspect SGI cares not one whit about PREEMPT. > Why does PREEMPT_RT require migrate_disable() but PREEMPT only is fine > as-is? This does not look right. UV is not ok with a PREEMPT config, it's just that for RT it's dirt simple to shut it up, whereas for PREEMPT, preempt_disable() across uv_bau_init() doesn't cut it due to allocations, and whatever else I would have met before ending the whack-a-mole game. If I were in your shoes, I think I'd just stop caring about UV until a real user appears. AFAIK, I'm the only guy who ever ran RT on UV, and I only did so because SUSE asked me to look into it.. years ago now. -Mike