Re: [PATCH] sched/fair: Consider cpu affinity when allowing NUMA imbalance in find_idlest_group

From: K Prateek Nayak
Date: Wed Feb 09 2022 - 07:10:27 EST


Hello Peter,

On 2/9/2022 4:16 PM, Peter Zijlstra wrote:
> On Mon, Feb 07, 2022 at 09:29:21PM +0530, K Prateek Nayak wrote:
>> Neither the sched/tip nor Mel's v5 patchset [1] provides an optimal
>> new-task wakeup strategy when the tasks are affined to a subset of cpus
>> which can result in piling of tasks on the same set of CPU in a NUMA
>> group despite there being other cpus in a different NUMA group where the
>> task could have run in.
> Where does this affinity come from?

The affinity comes from limiting the process to run on certain subset
of available cpus by modifying the cpus_ptr member of task_struck
of process via taskset or numactl.

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Thanks and Regards
Prateek