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 X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 35EF3C433DF for ; Wed, 13 May 2020 16:47:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7F09A205ED for ; Wed, 13 May 2020 16:47:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589388470; bh=EGUfcltCzqJGbjEtMpr4o9DdaPYtdN4oqY3dM2UkolY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ioKp/H/O4x8hkQheUnc3hCWccSZkCwiDX9baO9W3+ztib8OtdiGWP9zCpVL1g15EG 7GJ8Iz3yCtbalQ/+I5ugEr4pn5fLgyUeX68pS9KCaa+lCzialD3aiOEPPZb6awGeXs z2l2TVhOw/0NkV+fzCzKJkruvlvXw4BO4FFfvx2c= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389802AbgEMQrt (ORCPT ); Wed, 13 May 2020 12:47:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:53558 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389760AbgEMQrd (ORCPT ); Wed, 13 May 2020 12:47:33 -0400 Received: from lenoir.home (lfbn-ncy-1-985-231.w90-101.abo.wanadoo.fr [90.101.63.231]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E74962065D; Wed, 13 May 2020 16:47:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589388453; bh=EGUfcltCzqJGbjEtMpr4o9DdaPYtdN4oqY3dM2UkolY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=buuuJbVeDzw096UM/5n5bYclZ9Tv0M1T0TiI25fpRThygLhVS1qZCIwb1yVlmUbaZ 9pYWemSTTwHq6YhfVYkHceUE7quEr9R9KbPKxdAknUOg6I3MO/aR+WCYWml+l3nwls g1yanWkzmH4n5aoRBp5rJjYqHrHGhDIbzSL7UoR0= From: Frederic Weisbecker To: "Paul E . McKenney" Cc: LKML , Frederic Weisbecker , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , Josh Triplett Subject: [PATCH 07/10] rcu: Temporarily assume that nohz full CPUs might not be NOCB Date: Wed, 13 May 2020 18:47:11 +0200 Message-Id: <20200513164714.22557-8-frederic@kernel.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200513164714.22557-1-frederic@kernel.org> References: <20200513164714.22557-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org So far nohz_full CPUs had to be nocb. This requirement may change temporarily as we are working on preparing RCU to be able to toggle the nocb state of a CPU. Once that is done and nohz_full can be toggled as well dynamically, we'll restore that initial requirement. Thus for now as a temporary state, make rcu_nohz_full_cpu() aware of nohz_full CPUs that are not nocb so that they can handle the callbacks locally. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Josh Triplett Cc: Steven Rostedt Cc: Mathieu Desnoyers Cc: Lai Jiangshan Cc: Joel Fernandes --- kernel/rcu/tree.c | 2 +- kernel/rcu/tree.h | 2 +- kernel/rcu/tree_plugin.h | 7 ++++--- 3 files changed, 6 insertions(+), 5 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index cc95419f6491..74b6798309ef 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3223,7 +3223,7 @@ static int rcu_pending(int user) return 1; /* Is this a nohz_full CPU in userspace or idle? (Ignore RCU if so.) */ - if ((user || rcu_is_cpu_rrupt_from_idle()) && rcu_nohz_full_cpu()) + if ((user || rcu_is_cpu_rrupt_from_idle()) && rcu_nohz_full_cpu(rdp)) return 0; /* Is the RCU core waiting for a quiescent state from this CPU? */ diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 9dc2ec021da5..4b9643d9f5e0 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -451,7 +451,7 @@ do { \ #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */ static void rcu_bind_gp_kthread(void); -static bool rcu_nohz_full_cpu(void); +static bool rcu_nohz_full_cpu(struct rcu_data *rdp); static void rcu_dynticks_task_enter(void); static void rcu_dynticks_task_exit(void); diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 43ecc047af26..f19e81e0c691 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2532,13 +2532,14 @@ static void show_rcu_nocb_state(struct rcu_data *rdp) * The idea is to avoid waking up RCU core processing on such a * CPU unless the grace period has extended for too long. * - * This code relies on the fact that all NO_HZ_FULL CPUs are also - * CONFIG_RCU_NOCB_CPU CPUs. + * This code relies on the fact that NO_HZ_FULL CPUs might not + * be CONFIG_RCU_NOCB_CPU CPUs (temporary development state). */ -static bool rcu_nohz_full_cpu(void) +static bool rcu_nohz_full_cpu(struct rcu_data *rdp) { #ifdef CONFIG_NO_HZ_FULL if (tick_nohz_full_cpu(smp_processor_id()) && + rcu_segcblist_is_offloaded(&rdp->cblist) && (!rcu_gp_in_progress() || ULONG_CMP_LT(jiffies, READ_ONCE(rcu_state.gp_start) + HZ))) return true; -- 2.25.0