* Siddha, Suresh B <[email protected]> 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.
>
> Signed-off-by: Suresh Siddha <[email protected]>
nice catch!
fine for -mm, but i dont think we need this fix in 2.6.13, as the effect
of the bug is an extra context-switch per 'CPU goes idle' event, in this
very specific (and arguably broken) task binding scenario. In a
worst-case scenario a CPU going idle can 'spam' that other CPU with
migration requests, but it still seems like a pretty artificial workload
scenario where the system has significant idle time left. I have tested
your fix on a HT box and it solves the problem.
Acked-by: Ingo Molnar <[email protected]>
Ingo
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