Re: [PATCH v2] sched/eevdf: Prevent vlag from going out of bounds when reweight_eevdf

[Xuewen Yan]

On Mon, Apr 22, 2024 at 5:42 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> On Mon, Apr 22, 2024 at 04:33:37PM +0800, Xuewen Yan wrote:
>
> > On the Android system, the nice value of a task will change very
> > frequently. The limit can also be exceeded.
> > Maybe the !on_rq case is still necessary.
> > So I'm planning to propose another patch for !on_rq case later after
> > careful testing locally.
>
> So the scaling is: vlag = vlag * old_Weight / weight
>
> But given that integer devision is truncating, you could expect repeated
> application of such scaling would eventually decrease the vlag instead
> of grow it.
>
> Is there perhaps an invocation of reweight_task() missing? Looking at

Is it necessary to add reweight_task in the prio_changed_fair()?

> set_load_weight() I'm suspicious of the task_has_idle_policy() case.