LWN: Comments on "Soft CPU affinity"

Soft CPU affinity

post-factum — Wed, 10 Jul 2019 11:33:09 +0000

Why not just offload such a decision to some smaller userspace daemon?

Soft CPU affinity

valarauca — Tue, 09 Jul 2019 19:56:28 +0000

Isn't relocating memory & changing NUMA masks already be part of this process?

Presumably hot-plugging is already migrating memory prior to the CPU being removed, (or so I assume; without the on-cpu memory controller, the EC-DRAM will blank). Or is RAM kept live during a hot-plug?

Soft CPU affinity

zlynx — Tue, 09 Jul 2019 01:07:56 +0000

CPU hot-plug removal, with affine processes.

Soft CPU affinity

maxfragg — Mon, 08 Jul 2019 06:06:32 +0000

Sounds like a hard sell.
On paper having a soft cpu affinity might sound useful, but in my experience, in most cases where people want to pin their tasks, they don't want any heuristics which might cause strange side-effects. Predicting when an application will break out of its soft affinity and how this will affect such a fine tuned system might cause more trouble than it is worth