Re: [PATCH 1/2] sched/isolation: Merge individual nohz_full features into a common housekeeping flag

[Michal Koutný]

On Tue, Feb 07, 2023 at 12:49:41PM +0100, Frederic Weisbecker <frederic@xxxxxxxxxx> wrote:
> But what do we need these annotations for? The only outcome I've ever
> seen with these is that it confuses everyone.

Take that as a note of a lone actor then who found it useful documenting
relations between various parts of the code.

> This way I can add the support for each part smoothly.

Yeah, that makes sense.

> For example first patch moves HK_TYPE_TIMER to HK_TYPE_KERNEL_NOISE
> and unbound timers are supported by cpuset.kernel_noise, second patch
> moves HK_TYPE_WQ to HK_TYPE_KERNEL_NOISE and unbound workqueues are
> supported by cpuset.kernel_noise, etc until all of them turned by
> nohz_full= are supported...

So does this mean you'll re-introduce the finer grained HK_* flags
again?

The idea (not only mine?) is that this would extend
cpuset.cpus.partition that only allows HK_TYPE_DOMAIN analogy. The
mapping to individual flags may not be exposed to users. The graduality
could be achieved by adding more flags under user_exposed_term.

Just to be on the same page -- that's how I understand it, the original
HK_* resolution turned out impractical for users and that's why the
direction is towards some loose combinations representing user
intentions. Is that right?


Cheers,
Michal

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