Re: [PATCH v4 3/4] sched/isolation: Consolidate housekeeping cpumasks that are always identical

[Frederic Weisbecker <frederic@kernel.org>]

Le Sat, Sep 21, 2024 at 03:07:19PM -0400, Waiman Long a écrit :
> The housekeeping cpumasks are only set by two boot commandline
> parameters: "nohz_full" and "isolcpus". When there is more than one of
> "nohz_full" or "isolcpus", the extra ones must have the same CPU list
> or the setup will fail partially.
> 
> The HK_TYPE_DOMAIN and HK_TYPE_MANAGED_IRQ types are settable by
> "isolcpus" only and their settings can be independent of the other
> types. The other housekeeping types are all set by "nohz_full" or
> "isolcpus=nohz" without a way to set them individually. So they all
> have identical cpumasks.
> 
> There is actually no point in having different cpumasks for these
> "nohz_full" only housekeeping types. Consolidate these types to use the
> same cpumask by aliasing them to the same value. If there is a need to
> set any of them independently in the future, we can break them out to
> their own cpumasks again.
> 
> With this change, the number of cpumasks in the housekeeping structure
> drops from 9 to 3. Other than that, there should be no other functional
> change.
> 
> Signed-off-by: Waiman Long <longman@redhat.com>

Acked-by: Frederic Weisbecker <frederic@kernel.org>