From patchwork Mon Sep 16 22:49:20 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frederic Weisbecker X-Patchwork-Id: 13805814 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BD97F185941; Mon, 16 Sep 2024 22:50:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726527018; cv=none; b=j6paS4czn7c6lwaOiLOOpAkfQ1QILrSegzug5Tqc6B19fwdsn/IgcsTrNdWlXHpJiXPzhIQHWwe1BoGwxT6Qpo7BPSn3UyLp1He+h7GVvPfNsPCAfFMLb6ExBCmVyNrn8Q5pWfRO2G2nApiS5//6clIcIwJ8WH0am6/DWN0EYYg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726527018; c=relaxed/simple; bh=Mw6IdpbwGLq1RISXT+d8VcHFgzrRy+Z/Ckwqp68TP0c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ocSxVQl61NBUYfYIQNGpfuFgwzLQjjRo93C2REyDQFPZaxjQOCma6U5ix8snfZejnkjojxHkHiEg8+/S0V/HK6ZP1FnMjuZ3L6tSajoL+hxjtYtE1hWBDmi0HaE9sMXhbABW3t7Sa5Lu25CwPwMrdG8dnSe1Dpfaze/A8pZtYJM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=epHXqqz3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="epHXqqz3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE484C4CEC4; Mon, 16 Sep 2024 22:50:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1726527018; bh=Mw6IdpbwGLq1RISXT+d8VcHFgzrRy+Z/Ckwqp68TP0c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=epHXqqz3P/8BrDKsd/3NALffjMH7oqmeWMYk5NcM1tn2JN//nXg+2TkkO6JXQG3Q6 12OSX0iDWf2a1QXRS1qpqqR8fvvESIfKXuJlszihEIp7qsefH3D9RTAc42LprUnH/i e9hLDio74cgQ4vpkQ/WfNC2DODkmDU00VUkmtukGRUd0pEShoG+s0YDn6MciALD6dG Jd4qR2VlASNdZ2uzTktkkX0NNEZaPFOcj1ahcelpV4PW4jfSf8bqzdZmXP0GquQ3xu OVvoslSnYnPokqXlhV1l4wzvF5pHKp59J0MRC9RIK0o6mGBt2qo/g2GyLncO0/PaND 9XEws5sgcDHcQ== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , "Paul E. McKenney" , Neeraj Upadhyay , Joel Fernandes , Boqun Feng , Zqiang , rcu@vger.kernel.org, Andrew Morton , Peter Zijlstra , Thomas Gleixner Subject: [PATCH 16/19] rcu: Use kthread preferred affinity for RCU boost Date: Tue, 17 Sep 2024 00:49:20 +0200 Message-ID: <20240916224925.20540-17-frederic@kernel.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240916224925.20540-1-frederic@kernel.org> References: <20240916224925.20540-1-frederic@kernel.org> Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Now that kthreads have an infrastructure to handle preferred affinity against CPU hotplug and housekeeping cpumask, convert RCU boost to use it instead of handling all the constraints by itself. Acked-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker --- kernel/rcu/tree.c | 27 +++++++++++++++++++-------- kernel/rcu/tree_plugin.h | 11 ++--------- 2 files changed, 21 insertions(+), 17 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index e641cc681901..945e196090ed 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -149,7 +149,6 @@ static int rcu_scheduler_fully_active __read_mostly; static void rcu_report_qs_rnp(unsigned long mask, struct rcu_node *rnp, unsigned long gps, unsigned long flags); -static struct task_struct *rcu_boost_task(struct rcu_node *rnp); static void invoke_rcu_core(void); static void rcu_report_exp_rdp(struct rcu_data *rdp); static void sync_sched_exp_online_cleanup(int cpu); @@ -4932,6 +4931,22 @@ int rcutree_prepare_cpu(unsigned int cpu) return 0; } +static void rcu_thread_affine_rnp(struct task_struct *t, struct rcu_node *rnp) +{ + cpumask_var_t affinity; + int cpu; + + if (!zalloc_cpumask_var(&affinity, GFP_KERNEL)) + return; + + for_each_leaf_node_possible_cpu(rnp, cpu) + cpumask_set_cpu(cpu, affinity); + + kthread_affine_preferred(t, affinity); + + free_cpumask_var(affinity); +} + /* * Update kthreads affinity during CPU-hotplug changes. * @@ -4951,19 +4966,18 @@ static void rcutree_affinity_setting(unsigned int cpu, int outgoingcpu) unsigned long mask; struct rcu_data *rdp; struct rcu_node *rnp; - struct task_struct *task_boost, *task_exp; + struct task_struct *task_exp; rdp = per_cpu_ptr(&rcu_data, cpu); rnp = rdp->mynode; - task_boost = rcu_boost_task(rnp); task_exp = rcu_exp_par_gp_task(rnp); /* - * If CPU is the boot one, those tasks are created later from early + * If CPU is the boot one, this task is created later from early * initcall since kthreadd must be created first. */ - if (!task_boost && !task_exp) + if (!task_exp) return; if (!zalloc_cpumask_var(&cm, GFP_KERNEL)) @@ -4985,9 +4999,6 @@ static void rcutree_affinity_setting(unsigned int cpu, int outgoingcpu) if (task_exp) set_cpus_allowed_ptr(task_exp, cm); - if (task_boost) - set_cpus_allowed_ptr(task_boost, cm); - mutex_unlock(&rnp->kthread_mutex); free_cpumask_var(cm); diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index c569da65b421..d1ff1b982ca2 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1216,16 +1216,13 @@ static void rcu_spawn_one_boost_kthread(struct rcu_node *rnp) raw_spin_lock_irqsave_rcu_node(rnp, flags); rnp->boost_kthread_task = t; raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + sp.sched_priority = kthread_prio; sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); + rcu_thread_affine_rnp(t, rnp); wake_up_process(t); /* get to TASK_INTERRUPTIBLE quickly. */ } -static struct task_struct *rcu_boost_task(struct rcu_node *rnp) -{ - return READ_ONCE(rnp->boost_kthread_task); -} - #else /* #ifdef CONFIG_RCU_BOOST */ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags) @@ -1242,10 +1239,6 @@ static void rcu_spawn_one_boost_kthread(struct rcu_node *rnp) { } -static struct task_struct *rcu_boost_task(struct rcu_node *rnp) -{ - return NULL; -} #endif /* #else #ifdef CONFIG_RCU_BOOST */ /*