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=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 925CAC433B4 for ; Tue, 11 May 2021 22:53:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 75AC961421 for ; Tue, 11 May 2021 22:53:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230428AbhEKWyo (ORCPT ); Tue, 11 May 2021 18:54:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:33936 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230316AbhEKWyP (ORCPT ); Tue, 11 May 2021 18:54:15 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 144A36193D; Tue, 11 May 2021 22:53:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620773587; bh=whIQ3iED4fSPGIJAPepnQBHs4PtIh3o4kkhi3aBaxO0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NA9rKGsKVz0hYFot2+V6tt8JP7EbP86zvyLwBvXNhqMUfDF2kogDO/lbPKqZVJ7jV XR56jzDHvns0tj5x9xwepZGWAUTYmp2Kqtkx4nJ1TrHOLZeNoNdOx77gnk2NzkKyHJ jMh4BLxkddefwzAeSQKoOXRzEP+mssIunyr2/sywnSbEF2kp9Rfrp9tCPoTN18942V zI6T3zx0AIZzOsO25YecwwiCCKJgjXHiMXQfPd0Z9bDjERZivO4diCJkSyzF0WJQeV mmNnc+SlF7YwZqRm6DMnSMNDJtGKUZvfz2fkaisLngabYo7jWIMjX3GXNcKvML4kGi aRh1vNayuhHaQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 97A505C0DE7; Tue, 11 May 2021 15:53:06 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 09/19] rcu: Add quiescent states and boost states to show_rcu_gp_kthreads() output Date: Tue, 11 May 2021 15:52:54 -0700 Message-Id: <20210511225304.2893154-9-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20210511225241.GA2893003@paulmck-ThinkPad-P17-Gen-1> References: <20210511225241.GA2893003@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 This commit adds each rcu_node structure's ->qsmask and "bBEG" output indicating whether: (1) There is a boost kthread, (2) A reader needs to be (or is in the process of being) boosted, (3) A reader is blocking an expedited grace period, and (4) A reader is blocking a normal grace period. This helps diagnose RCU priority boosting failures. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.h | 1 + kernel/rcu/tree_plugin.h | 1 + kernel/rcu/tree_stall.h | 12 +++++++++--- 3 files changed, 11 insertions(+), 3 deletions(-) diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 71821d59d95c..5fd0c443517e 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -115,6 +115,7 @@ struct rcu_node { /* boosting for this rcu_node structure. */ unsigned int boost_kthread_status; /* State of boost_kthread_task for tracing. */ + unsigned long n_boosts; /* Number of boosts for this rcu_node structure. */ #ifdef CONFIG_RCU_NOCB_CPU struct swait_queue_head nocb_gp_wq[2]; /* Place for rcu_nocb_kthread() to wait GP. */ diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 2cbe8f8456e6..ef004cc7101d 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1098,6 +1098,7 @@ static int rcu_boost(struct rcu_node *rnp) /* Lock only for side effect: boosts task t's priority. */ rt_mutex_lock(&rnp->boost_mtx); rt_mutex_unlock(&rnp->boost_mtx); /* Then keep lockdep happy. */ + rnp->n_boosts++; return READ_ONCE(rnp->exp_tasks) != NULL || READ_ONCE(rnp->boost_tasks) != NULL; diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index a4e2bb3bdce7..c1f83864a18e 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -749,9 +749,15 @@ void show_rcu_gp_kthreads(void) if (ULONG_CMP_GE(READ_ONCE(rcu_state.gp_seq), READ_ONCE(rnp->gp_seq_needed))) continue; - pr_info("\trcu_node %d:%d ->gp_seq %ld ->gp_seq_needed %ld\n", - rnp->grplo, rnp->grphi, (long)data_race(rnp->gp_seq), - (long)data_race(rnp->gp_seq_needed)); + pr_info("\trcu_node %d:%d ->gp_seq %ld ->gp_seq_needed %ld ->qsmask %#lx %c%c%c%c ->n_boosts %ld\n", + rnp->grplo, rnp->grphi, + (long)data_race(rnp->gp_seq), (long)data_race(rnp->gp_seq_needed), + data_race(rnp->qsmask), + ".b"[!!data_race(rnp->boost_kthread_task)], + ".B"[!!data_race(rnp->boost_tasks)], + ".E"[!!data_race(rnp->exp_tasks)], + ".G"[!!data_race(rnp->gp_tasks)], + data_race(rnp->n_boosts)); if (!rcu_is_leaf_node(rnp)) continue; for_each_leaf_node_possible_cpu(rnp, cpu) { -- 2.31.1.189.g2e36527f23