Re: [GIT PULL] scheduler fixes

Valentin Schneider
2019-11-17T10:20:04Z

On 17/11/2019 09:45, Ingo Molnar wrote:
> I've picked v2 up instead. I suspect it's not really consequential as
> enums don't really get truncated by compilers, right? Is there any other
> negative runtime side effect possible from the imprecise enum/uint
> typing?
>

AFAIUI the requirement for the enum type is that it has to be an int type that
covers all its values, so I could see some funky optimization (e.g. check the
returned value is < 512 but it's assumed the type for the enum is 8 bits so
this becomes always true). Then again we don't have any explicit check on
those returned values, plus they fit in 11 bits, so as you say it's
mostly likely inconsequential (and I didn't see any compile diff).

My "worry" wasn't really about this patch, it was more about the following
one - it didn't like the idea of merging an unneeded patch (with a Fixes:
tag on top of it).

>>> sched/topology, cpuset: Account for housekeeping CPUs to avoid empty cpumasks
>>
>> And this one is no longer needed, as Michal & I understood (IOW the fix in
>> rc6 is sufficient), see:
>>
>> c425c5cb-ba8a-e5f6-d91c-5479779cfb7a@arm.com
>
> Ok.
>
> I'm inclined to just reduce sched/urgent back to these three fixes:
>
> 6e1ff0773f49: sched/uclamp: Fix incorrect condition
> b90f7c9d2198: sched/pelt: Fix update of blocked PELT ordering
> ff51ff84d82a: sched/core: Avoid spurious lock dependencies
>
> and apply v2 of the uclamp_id type fix to sched/core. This would reduce
> the risks of a Sunday pull request ...
>

This sounds good to me. Sorry for the hassle.

> Thanks,
>
> Ingo
>