Re: [RFC][PATCH 13/16] sched: Add core wide task selection and scheduling.

Aaron Lu
2019-04-10T04:36:45Z

On Tue, Apr 09, 2019 at 11:09:45AM -0700, Tim Chen wrote:
> Now that we have accumulated quite a number of different fixes to your orginal
> posted patches. Would you like to post a v2 of the core scheduler with the fixes?

One more question I'm not sure: should a task with cookie=0, i.e. tasks
that are untagged, be allowed to scheduled on the the same core with
another tagged task?

The current patch seems to disagree on this, e.g. in pick_task(),
if max is already chosen but max->core_cookie == 0, then we didn't care
about cookie and simply use class_pick for the other cpu. This means we
could schedule two tasks with different cookies(one is zero and the
other can be tagged).

But then sched_core_find() only allow idle task to match with any tagged
tasks(we didn't place untagged tasks to the core tree of course :-).

Thoughts? Do I understand this correctly? If so, I think we probably
want to make this clear before v2. I personally feel, we shouldn't allow
untagged tasks(like kernel threads) to match with tagged tasks.