Re: [PATCH 1/2] sched/topology: Allow archs to override cpu_smt_mask

* peterz@infradead.org [off-list ref] [2020-08-06 15:15:47]:

quoted

But my understanding is most LPARs don't get migrated back and forth,
they'll start life on a P8 and only get migrated to a P9 once when the
customer gets a P9. They might then run for a long time (months to
years) on the P9 in P8 compat mode, not because they ever want to
migrate back to a real P8, but because the software in the LPAR is still
expecting to be on a P8.

I'm not a real expert on all the Enterprisey stuff though, so someone
else might be able to give us a better picture.

But the point of mentioning the migration stuff was mainly just to
explain why we feel we need to present SMT8 to userspace even on P9.

OK, fair enough. The patch wasn't particularly onerous, I was just
wondering why etc..

The case of starting on a P8 and being migrated to a P9 makes sense to
me; in that case you'd like to rebuild your sched domains, but can't go
about changing user visible topolofy information.

I suppose:

Acked-by; Peter Zijlstra (Intel) [off-list ref]

An updated Changelog that recaps some of this discussion might also be
nice.

Okay, will surely do the needful.

-- 
Thanks and Regards
Srikar Dronamraju