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

Phil Auld
2024-08-07T21:04:52Z

Hi Tejun,

On Wed, Aug 07, 2024 at 09:26:28AM -1000 Tejun Heo wrote:
> 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! That would be helpful. I was going to offer a patch but wanted to ask first
in case there was history.

But if you are willing to do it that's even better :)

Cheers,
Phil

>
> Thanks.
>
> --
> tejun
>

--