Re: [PATCH] sched_ext: Add scx_bpf_task_add_dsq_vtime()

[Cheng-Yang Chou <yphbchou0911@gmail.com>]

Hi Andrea,

On Wed, Mar 11, 2026 at 04:58:27PM +0100, Andrea Righi wrote:
> Hm, I'm not sure we need a dedicated kfunc for this. Sub-schedulers can
> read p->scx.slice and p->scx.dsq_vtime from any task, they just can't
> modify those values for the tasks they don't own.
> 
> So they could read the current value, apply the delta, and then use
> scx_bpf_task_set_*() to update it.
> 
> Am I missing something here?

Oh I see.

My original thought was just to make the API a bit more convenient.
Instead of writing:

    scx_bpf_task_set_dsq_vtime(p, p->scx.dsq_vtime + delta);

Developers could simply write:

    scx_bpf_task_add_dsq_vtime(p, delta);

But as you pointed out, the set() helper is already a straightforward
one-liner and functionally identical. The authority check is also
properly handled.

I am totally fine with dropping this patch.

-- 
Thanks,
Cheng-Yang