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

Tejun Heo
2024-08-07T19:26:31Z

Hello, Phil.

On Wed, Aug 07, 2024 at 03:11:08PM -0400, Phil Auld wrote:
> 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.

Yeap and great to hear.

> 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.

Sure, that's not difficult. Will do so soon.

Thanks.

--
tejun