From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DFBE4C4332F for ; Wed, 13 Dec 2023 01:06:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377727AbjLMBGV (ORCPT ); Tue, 12 Dec 2023 20:06:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235196AbjLMBGS (ORCPT ); Tue, 12 Dec 2023 20:06:18 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6D10ACE for ; Tue, 12 Dec 2023 17:06:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1702429584; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=D0SnZLCy81+dYJzS4wut67vLKnCWkGca6Y+iC19IrjA=; b=DeH0wR79US59/2WBkbxR/aQNh08C3UzJ4YICFjcuMDuX+Q/uWoMn6nkCkAKjMozMoVqNWz Z7E2RUKVXiR5T9SRonvuCv+NiXgpMeoJg0nnO3Qv2fPX+YB/Jiwf6argBfviJ3rxosNkrh MGDGFKc1lmLm2oH/49B7vddIghL5C7s= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-75--M6I3TC7ONq7bLk6cP72TQ-1; Tue, 12 Dec 2023 20:06:20 -0500 X-MC-Unique: -M6I3TC7ONq7bLk6cP72TQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 33A5E8489E4; Wed, 13 Dec 2023 01:06:20 +0000 (UTC) Received: from fedora (unknown [10.72.116.39]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D49583C25; Wed, 13 Dec 2023 01:06:16 +0000 (UTC) Date: Wed, 13 Dec 2023 09:06:12 +0800 From: Ming Lei To: Yury Norov Cc: Andrew Morton , Thomas Gleixner , linux-kernel@vger.kernel.org, Andy Shevchenko , Rasmus Villemoes Subject: Re: [PATCH v3 7/7] lib/group_cpus: simplify grp_spread_init_one() for more Message-ID: References: <20231212042108.682072-1-yury.norov@gmail.com> <20231212042108.682072-8-yury.norov@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231212042108.682072-8-yury.norov@gmail.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 11, 2023 at 08:21:07PM -0800, Yury Norov wrote: > The outer and inner loops of grp_spread_init_one() do the same thing - > move a bit from nmsk to irqmsk. > > The inner loop iterates the sibling group, which includes the CPU picked > by outer loop. And it means that we can drop the part that moves the bit > in the outer loop. > > Signed-off-by: Yury Norov > --- > lib/group_cpus.c | 8 +------- > 1 file changed, 1 insertion(+), 7 deletions(-) > > diff --git a/lib/group_cpus.c b/lib/group_cpus.c > index 664a56171a1b..7aa7a6289355 100644 > --- a/lib/group_cpus.c > +++ b/lib/group_cpus.c > @@ -18,14 +18,8 @@ static void grp_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk, > int cpu, sibl; > > for_each_cpu(cpu, nmsk) { > - __cpumask_clear_cpu(cpu, nmsk); > - __cpumask_set_cpu(cpu, irqmsk); > - if (cpus_per_grp-- == 0) > - return; > - > - /* If the cpu has siblings, use them first */ > siblmsk = topology_sibling_cpumask(cpu); > - sibl = cpu + 1; > + sibl = cpu; > > for_each_cpu_and_from(sibl, siblmsk, nmsk) { > __cpumask_clear_cpu(sibl, nmsk); Correctness of the above change requires that 'cpu' has to be included into topology_sibling_cpumask(cpu), however, not sure it is always true, see the following comment in Documentation/arch/x86/topology.rst ` - topology_sibling_cpumask(): The cpumask contains all online threads in the core to which a thread belongs. ` Thanks, Ming