Re: [PATCH sched_ext/for-7.4-fixes] sched_ext: Fix partial-SMT core counting in calc_shard_layout()

[Tejun Heo <tj@kernel.org>]

Hello, Qiao.

On Fri, Nov 06, 2026 at 10:44:30AM +0800, Zhang Qiao wrote:
> A core is counted when its cpu is the first cpu of
> topology_sibling_cpumask(), which includes offline cpus. When the

AFAICS topology_sibling_cpumask() includes offline cpus only on mips and
sparc64. x86, arm64, riscv, powerpc, loongarch and s390 clear an offlined
cpu from its siblings' masks. Which arch did you hit this on?

> +		/* the low-numbered siblings may be offline */
> +		if (cpumask_first_and(topology_sibling_cpumask(cpu),
> +				      llc_cpus) == cpu)

The comment describes one scenario rather than what the test does, which
isn't very useful. Can you state the rule instead? e.g.

  /*
   * scx_cid_init() forms each core from the siblings in
   * @llc_cpus. The sibling mask may include cpus outside
   * @llc_cpus, so count a core at its first sibling in @llc_cpus.
   */

The fix looks right, but the patch is whitespace damaged and doesn't
apply. Can you send v2 with git send-email?

Thanks.

--
tejun