Re: [PATCH 09/30] sched_ext: Implement BPF extensible scheduler class

Phil Auld
2024-08-07T19:11:29Z

Hi Tejun,

On Tue, Jun 18, 2024 at 11:17:24AM -1000 Tejun Heo wrote:
> Implement a new scheduler class sched_ext (SCX), which allows scheduling
> policies to be implemented as BPF programs to achieve the following:
>

I looks like this is slated for v6.12 now? That would be good. My initial
experimentation with scx has been positive.

I just picked one email, not completely randomly.

> - Both enable and disable paths are a bit complicated. The enable path
> switches all tasks without blocking to avoid issues which can arise from
> partially switched states (e.g. the switching task itself being starved).
> The disable path can't trust the BPF scheduler at all, so it also has to
> guarantee forward progress without blocking. See scx_ops_enable() and
> scx_ops_disable_workfn().

I think, from a supportability point of view, there needs to be a pr_info, at least,
in each of these places, enable and disable, with the name of the scx scheduler. It
looks like there is at least a pr_error for when one gets ejected due to misbehavior.
But there needs to be a record of when such is loaded and unloaded.

Thoughts?

Cheers,
Phil