[RFC] Core Scheduling unnecessary force idle?

From: Benjamin Tang
Date: Wed Nov 29 2023 - 03:53:44 EST


When I'm reading the code related to "core scheduling", I have a question.

Say the RQs in a particular core look like this:
Let CFS1 and CFS4 be 2 untagged CFS tasks.
Let CFS2 and CFS3 be 2 untagged CFS tasks.

         rq0                      rq1
    CFS1(no tag)     CFS3(tagged)
    CFS2(tagged)    CFS4(no tag)

Say schedule() runs on rq0. In the core-wide pick logic, if I'm not mistaken,
the end result of the selection will be (say prio(CFS1) > prio(CFS3)):

         rq0                 rq1
    CFS1(no tag)    IDLE

Why not consider trying to find untagged tasks for rq1 here?
Is it because it seems less fair, or are there other considerations?

I would be very grateful if someone could give me some suggestions.
Thanks!

Best Wishes