From patchwork Tue Nov 12 14:22:42 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frederic Weisbecker X-Patchwork-Id: 13872303 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 4813720103E; Tue, 12 Nov 2024 14:23:46 +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=1731421427; cv=none; b=MtGghF+xUGuT46xKCztTD2Kxarff/T6D4jQ2MqW0eruuMWhJ4UxS9jYtTymxxgSvicKLj1UmDwqZlzJvOzUzfKrz80LriKX5JJO/v6CAnwREMxXMZSUt/TLH6J7epATCCwOehV7vCY/lQ9Txx6NgQr+XEl0bUp2IIkhtvVTIfL4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731421427; c=relaxed/simple; bh=+DdjSv/NXaxI66NEqUc/nJJcmGjm5IN9uZnJrFqcZcI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BX0/2BMphiOjL03ct35lRSuMrculu84GCTK6LOeRtO5zeYcJ4CCXT6INVJf8cR7YJcq9wIndjg3Q95N1F6yUcOluuiDtKr6BxN63m8sj/UiLExVfC9+ROtJxSbzxzbPRDNY6G4mj5n0qHHIRvnlN4tnyKwKhZF1/Uw2es+XMRZs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bUd/v2Mt; 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="bUd/v2Mt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC52AC4CECD; Tue, 12 Nov 2024 14:23:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1731421426; bh=+DdjSv/NXaxI66NEqUc/nJJcmGjm5IN9uZnJrFqcZcI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bUd/v2MtzsSAUpnNGZTCF9YMlgvZak1Elz1aM2sR5Bw3s6QEj+DcsUqYulYOgCJrd mALq0J2iZsQNwD5M+x5kJhZT5FP71dQh5B/J7txEOtrM2bdkOSSsc7ztxvR/ehM35G X5a21mp1C0Cvh/JwXyHE/ttrfok0f4388+BQQm3YZmF+yOIAVZKa5hPfovEC1+avs2 uAWp4msU7c46B9oeu4/YTnZdbU6Uyl6jkBOhiMq9cPpkVQc8BSjmmwcOs/27UYqzsz awYZQp98Shu6ZQX2cwnlUloaOwcavFaaIkRsr1YOiq0/UyeyfxAejSPcCe863f5aYa Jz6pAkDDwPVZg== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , "Paul E. McKenney" , Uladzislau Rezki , Neeraj Upadhyay , Joel Fernandes , Boqun Feng , Zqiang , rcu@vger.kernel.org, Andrew Morton , Peter Zijlstra , Thomas Gleixner , Michal Hocko , Vlastimil Babka Subject: [PATCH 18/21] rcu: Use kthread preferred affinity for RCU boost Date: Tue, 12 Nov 2024 15:22:42 +0100 Message-ID: <20241112142248.20503-19-frederic@kernel.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20241112142248.20503-1-frederic@kernel.org> References: <20241112142248.20503-1-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 b1f883fcd918..c9fd28f0f068 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); @@ -5008,6 +5007,22 @@ 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. * @@ -5027,19 +5042,18 @@ 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)) @@ -5061,9 +5075,6 @@ 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 1c7cbd145d5e..223f3a02351e 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1217,16 +1217,13 @@ 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) @@ -1243,10 +1240,6 @@ 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 */ /*