Re: [RFC PATCH v1] sched/uclamp: Introduce SCHED_FLAG_RESET_UCLAMP_ON_FORK flag

[Qais Yousef <qyousef@layalina.io>]

On 04/19/23 18:54, Qais Yousef wrote:

[...]

> I was considering to have something a bit more generic that allows selecting
> which attributes to reset.
> 
> For example a syscall with SCHED_FLAG_RESET_ON_FORK_SEL combined with
> SCHED_FLAG_UCLAMP_MIN/MAX will only reset those. This should make it extensible
> if we have other similar use cases in the future. The downside it *might*
> require to be done in a separate syscall to the one that sets these parameter.
> But it should be done once.
> 
> Maybe there's a better interface, but I think it makes sense to do it in a way
> that we won't have to do this again. Would be good to hear from maintainers
> first before you take my word for it ;-)

Actually I think we can do a better and simpler generic interface. We don't
need a new flag. We can just add a new parameter for what to reset on fork.
When this value is 0 (which it should be by default), it means reset
everything.

// pseudo code

#define RESET_ON_FORK_ALL	0
#define RESET_ON_FORK_POLICY	BIT(1) // implies resetting priority
#define RESET_ON_FORK_PRIORITY	BIT(2)
#define RESET_ON_FORK_UCLAMP	BIT(3)

struct sched_attr {
	...
	__u64 sched_reset_on_fork_flags;
};


Cheers

--
Qais Yousef