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 0C0C5C4332F for ; Fri, 4 Feb 2022 23:24:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378117AbiBDXYL (ORCPT ); Fri, 4 Feb 2022 18:24:11 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:60958 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346197AbiBDXYK (ORCPT ); Fri, 4 Feb 2022 18:24:10 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 553CFB83973; Fri, 4 Feb 2022 23:24:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 07821C340F0; Fri, 4 Feb 2022 23:24:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644017048; bh=EnUP4evSm9pHbY5I/gW2mI3yvHr8E8M9zkokamOt2mo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LkD/mAKjCco9ffJfgdLcTqIeY8837S5n7V0mSJLhZ5dsqX6t4FeLKLlgU8O/XBU5p n8c0AiSdU13zdV5Hz6XX9z51F30/yMvu5CZUS1z0N4M+lDvHP+L9Yv0L+1wnoqLABI /e7Lq+VRyGbyMbfXg80LR366FfwpyV++HAZivjWsQ91LyPXB9sa0r4FZJjvpwgkpnH m0gb5rdpkuQqvLfpV8dN2/TzE2UbWn54dtBK2bR3D6L7DHWe8xCgJYF+jps5LBsC2r F52z5iD4RB7gs8TD0AXhZdnXH2cK4cW2NdHweTjegJiCqNoyFNu6diGEGcg15yurTH SHmH7tjNEhB7g== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id C58AB5C08DD; Fri, 4 Feb 2022 15:24:07 -0800 (PST) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, rostedt@goodmis.org, Zqiang , Sebastian Andrzej Siewior , "Paul E . McKenney" Subject: [PATCH rcu 04/10] rcu: Create per-cpu rcuc kthreads only when rcutree.use_softirq=0 Date: Fri, 4 Feb 2022 15:24:00 -0800 Message-Id: <20220204232406.814-4-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20220204232355.GA728@paulmck-ThinkPad-P17-Gen-1> References: <20220204232355.GA728@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zqiang The per-CPU "rcuc" kthreads are used only by kernels booted with rcutree.use_softirq=0, but they are nevertheless unconditionally created by kernels built with CONFIG_RCU_BOOST=y. This results in "rcuc" kthreads being created that are never actually used. This commit therefore refrains from creating these kthreads unless the kernel is actually booted with rcutree.use_softirq=0. Acked-by: Sebastian Andrzej Siewior Signed-off-by: Zqiang Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index a4c25a6283b0b..4e5e37e5ee3c9 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2894,7 +2894,7 @@ static int __init rcu_spawn_core_kthreads(void) for_each_possible_cpu(cpu) per_cpu(rcu_data.rcu_cpu_has_work, cpu) = 0; - if (!IS_ENABLED(CONFIG_RCU_BOOST) && use_softirq) + if (use_softirq) return 0; WARN_ONCE(smpboot_register_percpu_thread(&rcu_cpu_thread_spec), "%s: Could not start rcuc kthread, OOM is now expected behavior\n", __func__); -- 2.31.1.189.g2e36527f23