Re: [PATCH-cgroup 1/4] workqueue: Add workqueue_unbound_exclude_cpumask() to exclude CPUs from wq_unbound_cpumask

[Tejun Heo]

Hello,

On Wed, Oct 18, 2023 at 03:18:52PM -0400, Waiman Long wrote:
> I have a second thought after taking a further look at that. First of all,
> cpuset_allowed_mask isn't relevant here and the mask can certainly contain
> offline CPUs. So cpu_possible_mask is the proper fallback.
> 
> With the current patch, wq_user_unbound_cpumask is set up initially as 
> (HK_TYPE_WQ ∩ HK_TYPE_DOMAIN) house keeping mask and rewritten by any
> subsequent write to workqueue/cpumask sysfs file. So using

The current behavior is not something which is carefully planned. It's more
accidental than anything. If we can come up with a more intutive and
consistent behavior, that should be fine.

> wq_user_unbound_cpumask has the implied precedence of user-sysfs written
> mask, command line isolcpus or nohz_full option mask and cpu_possible_mask.
> I think just fall back to wq_user_unbound_cpumask if the operation fails
> should be enough.

But yeah, that sounds acceptable.

Thanks.

-- 
tejun