Re: [PATCH] sched/isolation: allow isolcpus and nohz_full for different cpus

[Frederic Weisbecker]

On Thu, Apr 16, 2020 at 04:51:18PM +0800, Li RongQing wrote:
> when both isolcpus and nohz_full are set, their cpus must be
> same now, in fact isolcpus and nohz_full are not related, and
> different cpus are expected for some cases, for example, some
> cores for polling threads wants to isolcpus, and some cores for
> dedicated threads, only nohz_full is expected
> 
> so define two housekeeping mask to save these two configuration
> separately and make cpus same only when both nohz_full and
> isolcpus with nohz are passed into kernel
> 
> fix a build error when CONFIG_CPUMASK_OFFSTACK is not configured
> reported by kbuild test robot <lkp@xxxxxxxxx>

What is the usecase when you want to affine managed interrupt?
Do you only want to affine IRQ or do you also want to affine
every unbound work, such as kthread, workqueues, timers, etc...?

In the end I would like to group the isolation features that only
make sense together. So we could end up with three cpumasks, one
for "domains", one for "nohz" and one for all "unbound" works.

In fact "domains" should even disappear and become "unbound" +
"load_balance", as that's the desired outcome of having NULL domains.

I'm trying to prepare a suitable interface for all that in cpusets
where we already have the load_balance part.

Thanks.