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Sender: Tejun Heo <htejun@gmail.com>
Date:   Sun, 11 Dec 2022 16:15:59 -1000
From:   Tejun Heo <tj@kernel.org>
To:     Julia Lawall <julia.lawall@inria.fr>
Cc:     torvalds@linux-foundation.org, mingo@redhat.com,
        peterz@infradead.org, juri.lelli@redhat.com,
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        linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
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Subject: Re: [PATCH 14/31] sched_ext: Implement BPF extensible scheduler class
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References: <20221130082313.3241517-1-tj@kernel.org>
 <20221130082313.3241517-15-tj@kernel.org>
 <alpine.DEB.2.22.394.2212112331150.29296@hadrien>
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Hello, Julia.

On Sun, Dec 11, 2022 at 11:33:50PM +0100, Julia Lawall wrote:
> > diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
> > new file mode 100644
> > index 000000000000..f42464d66de4
> > --- /dev/null
> > +++ b/kernel/sched/ext.c
> > @@ -0,0 +1,2780 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
> > + * Copyright (c) 2022 Tejun Heo <tj@kernel.org>
> > + * Copyright (c) 2022 David Vernet <dvernet@meta.com>
> > + */
> > +#define SCX_OP_IDX(op)		(offsetof(struct sched_ext_ops, op) / sizeof(void (*)(void)))
> > +
> > +enum scx_internal_consts {
> > +	SCX_NR_ONLINE_OPS	 = SCX_OP_IDX(init),
> > +	SCX_DSP_DFL_MAX_BATCH	 = 32,
> 
> This definition of SCX_DSP_DFL_MAX_BATCH makes the dispatch queue have size
> 32.  The example central policy thus aborts if more than 32 tasks are woken
> up at once.

Yeah, scx_exampl_central needs to either set ops.dispatch_max_batch higher
according to number of CPUs or flush and exit the loop and retry when
scx_bpf_dispatch_nr_slots() reaches zero. Will update.

Thanks.

-- 
tejun