From nobody Fri Nov 29 00:56:22 2024 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 80D001B29C9; Thu, 26 Sep 2024 22:50:00 +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=1727391000; cv=none; b=KZrgkC9+Aqqm8HI8KXPM1uppVOSiaNa6QFoP8055+7HWIkxV5OrXUFcsnO8gQhOMlseYF1OU3pXK5a8WYP4QCdhQmHg6mZsZHqGrRxnoxLz8A8hj9JHPoNICfQc5EeRmdjkZsjnO1Sicp8aMweybjEfoF8AjCbr/YVRkQNQduXo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727391000; c=relaxed/simple; bh=+P4kzizCeNOj1Ff6ZQgJUmeNr/qO1N9UQodOY09ijkk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=A6uSieDb1d3IYwuhG8+CiDIiK3SuveyzkyZ0DC35HBcdxd9kpck3wyXa0SHCB2P3sro5wcvA2B5m+hQbae3/H9K4DbG808wET9dESYW7JovMnXDUV9axXK6ECFX9hKng5NFEo3yT0g38qTGwNQoVEx69SU9jdD6DvDbv1tT9i2M= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PtxSAIGX; 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="PtxSAIGX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7DFA1C4CECE; Thu, 26 Sep 2024 22:49:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727391000; bh=+P4kzizCeNOj1Ff6ZQgJUmeNr/qO1N9UQodOY09ijkk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PtxSAIGXraxeSEcnRb5c6or1mDuRelDxeTl4uTsmPJoNX4SkfcLp8zfw6DI3U6IKo hGeCb0rW4cmP1twq+Q/Ux7r7kQ0c+3/feiQC/OFLvPd5+mPm44hnrWQpUEi8QAo2HN /AeZndBE6GOjR0iiD3XUIS4vvlr2Byt76Pi3DYp/LK1n/HKBKlFBZLyIVDhhYE25Mq 3uAyq78eTTKQ20XvaHSoz0+r7uc7qqhTighQfrX9aQgV7QWXOIO9K+FycdA466YzZY 1p5v51Na8Y6gMtVNn1HfNWfQLDlkNSi2OI/oAz7bcxdGDDVD2djD6m1wCqTBSno0yx 8rauYfzaiZfxw== 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 17/20] rcu: Use kthread preferred affinity for RCU boost Date: Fri, 27 Sep 2024 00:49:05 +0200 Message-ID: <20240926224910.11106-18-frederic@kernel.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240926224910.11106-1-frederic@kernel.org> References: <20240926224910.11106-1-frederic@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 a60616e69b66..c1e9f0818d51 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -149,7 +149,6 @@ static int rcu_scheduler_fully_active __read_mostly; =20 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); @@ -5007,6 +5006,22 @@ int rcutree_prepare_cpu(unsigned int cpu) return 0; } =20 +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. * @@ -5026,19 +5041,18 @@ static void rcutree_affinity_setting(unsigned int c= pu, 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; =20 rdp =3D per_cpu_ptr(&rcu_data, cpu); rnp =3D rdp->mynode; =20 - task_boost =3D rcu_boost_task(rnp); task_exp =3D rcu_exp_par_gp_task(rnp); =20 /* - * 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; =20 if (!zalloc_cpumask_var(&cm, GFP_KERNEL)) @@ -5060,9 +5074,6 @@ static void rcutree_affinity_setting(unsigned int cpu= , int outgoingcpu) if (task_exp) set_cpus_allowed_ptr(task_exp, cm); =20 - if (task_boost) - set_cpus_allowed_ptr(task_boost, cm); - mutex_unlock(&rnp->kthread_mutex); =20 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 =3D t; raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + sp.sched_priority =3D kthread_prio; sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); + rcu_thread_affine_rnp(t, rnp); wake_up_process(t); /* get to TASK_INTERRUPTIBLE quickly. */ } =20 -static struct task_struct *rcu_boost_task(struct rcu_node *rnp) -{ - return READ_ONCE(rnp->boost_kthread_task); -} - #else /* #ifdef CONFIG_RCU_BOOST */ =20 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_n= ode *rnp) { } =20 -static struct task_struct *rcu_boost_task(struct rcu_node *rnp) -{ - return NULL; -} #endif /* #else #ifdef CONFIG_RCU_BOOST */ =20 /* --=20 2.46.0