* Nick Piggin <[email protected]> wrote:
> Siddha, Suresh B wrote:
> >Jack Steiner brought this issue at my OLS talk.
> >
> >Take a scenario where two tasks are pinned to two HT threads in a physical
> >package. Idle packages in the system will keep kicking migration_thread
> >on the busy package with out any success.
> >
> >We will run into similar scenarios in the presence of CMP/NUMA.
> >
> >Patch appended.
> >
>
> Hmm, I would have hoped the new "all_pinned" logic should have handled
> this case properly. [...]
no, active_balance is a different case, not covered by the all_pinned
logic. This is a HT-special scenario, where busiest->nr_running == 1,
and we have to do active load-balancing. This does not go through
move_tasks() and does not set all_pinned. (If nr_running werent 1 we'd
not have to kick active load-balancing.)
Ingo
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