Re: [RFC PATCH v5 0/9] steal tasks to improve CPU utilization

[Valentin Schneider]

On 20/03/26 09:53, Peter Zijlstra wrote:
> On Fri, Mar 20, 2026 at 05:59:11AM +0000, Chen Jinghuang wrote:
>> When a CPU has no more CFS tasks to run, and idle_balance() fails to
>> find a task, then attempt to steal a task from an overloaded CPU in the
>> same LLC. Maintain and use a bitmap of overloaded CPUs to efficiently
>> identify candidates.  To minimize search time, steal the first migratable
>> task that is found when the bitmap is traversed.  For fairness, search
>> for migratable tasks on an overloaded CPU in order of next to run.
>
> This makes no sense. It is the task of newidle to get more work -- if
> that is failing for you, then we should fix that, not build a second way
> to get tasks.

Yeah I don't recall exactly how it was stitched together, but IIRC Steve's
patches had stealing as the default newidle balance up until we got to NUMA
balancing because it acted funny there.