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

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Message-ID: <ZrPKZMvrl6kGFzo-@slm.duckdns.org>
Date: Wed, 7 Aug 2024 09:26:28 -1000
From: Tejun Heo <tj@...nel.org>
To: Phil Auld <pauld@...hat.com>
Cc: torvalds@...ux-foundation.org, mingo@...hat.com, peterz@...radead.org,
	juri.lelli@...hat.com, vincent.guittot@...aro.org,
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Subject: Re: [PATCH 09/30] sched_ext: Implement BPF extensible scheduler class

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