From patchwork Fri Mar 24 00:19:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 13186203 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F182C761AF for ; Fri, 24 Mar 2023 00:20:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231375AbjCXAUK (ORCPT ); Thu, 23 Mar 2023 20:20:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58420 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231350AbjCXAT7 (ORCPT ); Thu, 23 Mar 2023 20:19:59 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B871D2E0DE; Thu, 23 Mar 2023 17:19:50 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A0634B822B4; Fri, 24 Mar 2023 00:19:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B765C433AF; Fri, 24 Mar 2023 00:19:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1679617181; bh=MAdfEhnT/3cOhBFkqmfwCHXtUyR9uHGuueAhpuWvzO8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DZvZzEbCURXVTVMgdsW0b4RUQqRZQC8Gxdn3yZSP2HpWQH0YR3aadA+gWCTkLpCAb yN5LowvL9vTfqLTL2IqosQf7S6HpCFJAoHG0CJk4FlsWQzOMn2fOXq77PWtnGw45IK dnEXnSkv1G/k876/cMUVWwG52OWGNhl40NczbU0EZD7Oa2olWCOq5Fcdm/wbIaqqw6 zYjLPh24yS1gR5qTU7yEHHhOnvFZokJIWJH5yyT1gdbsuV8h0JQf/41rQ7J1ZYL5kR +CfDjQBV0nWLc0DG8ZWSIhLed2ux12RnLILG+glMaEyC98sRcM+OiTJ0+CqipveKxx BsJp3ai+R4Vyg== Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id B693A15403A6; Thu, 23 Mar 2023 17:19:40 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, hch@lst.de, "Paul E. McKenney" Subject: [PATCH RFC rcu 13/19] srcu: Move srcu_barrier() fields from srcu_struct to srcu_usage Date: Thu, 23 Mar 2023 17:19:32 -0700 Message-Id: <20230324001938.3443499-13-paulmck@kernel.org> X-Mailer: git-send-email 2.40.0.rc2 In-Reply-To: <3db82572-f156-4a5d-b711-841aa28bd996@paulmck-laptop> References: <3db82572-f156-4a5d-b711-841aa28bd996@paulmck-laptop> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org This commit moves the ->srcu_barrier_seq, ->srcu_barrier_mutex, ->srcu_barrier_completion, and ->srcu_barrier_cpu_cnt fields from the srcu_struct structure to the srcu_usage structure to reduce the size of the former in order to improve cache locality. Suggested-by: Christoph Hellwig Signed-off-by: Paul E. McKenney --- include/linux/srcutree.h | 14 +++++++------- kernel/rcu/srcutree.c | 38 +++++++++++++++++++------------------- 2 files changed, 26 insertions(+), 26 deletions(-) diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h index ca48b97d9f3b..70f5a3abe80a 100644 --- a/include/linux/srcutree.h +++ b/include/linux/srcutree.h @@ -77,6 +77,13 @@ struct srcu_usage { unsigned long srcu_n_lock_retries; /* Contention events in current interval. */ unsigned long srcu_n_exp_nodelay; /* # expedited no-delays in current GP phase. */ bool sda_is_static; /* May ->sda be passed to free_percpu()? */ + unsigned long srcu_barrier_seq; /* srcu_barrier seq #. */ + struct mutex srcu_barrier_mutex; /* Serialize barrier ops. */ + struct completion srcu_barrier_completion; + /* Awaken barrier rq at end. */ + atomic_t srcu_barrier_cpu_cnt; /* # CPUs not yet posting a */ + /* callback for the barrier */ + /* operation. */ }; /* @@ -85,13 +92,6 @@ struct srcu_usage { struct srcu_struct { unsigned int srcu_idx; /* Current rdr array element. */ struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */ - unsigned long srcu_barrier_seq; /* srcu_barrier seq #. */ - struct mutex srcu_barrier_mutex; /* Serialize barrier ops. */ - struct completion srcu_barrier_completion; - /* Awaken barrier rq at end. */ - atomic_t srcu_barrier_cpu_cnt; /* # CPUs not yet posting a */ - /* callback for the barrier */ - /* operation. */ unsigned long reschedule_jiffies; unsigned long reschedule_count; struct delayed_work work; diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 7c192f7fb559..1df4a1467765 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -248,9 +248,9 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) mutex_init(&ssp->srcu_sup->srcu_gp_mutex); ssp->srcu_idx = 0; ssp->srcu_sup->srcu_gp_seq = 0; - ssp->srcu_barrier_seq = 0; - mutex_init(&ssp->srcu_barrier_mutex); - atomic_set(&ssp->srcu_barrier_cpu_cnt, 0); + ssp->srcu_sup->srcu_barrier_seq = 0; + mutex_init(&ssp->srcu_sup->srcu_barrier_mutex); + atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0); INIT_DELAYED_WORK(&ssp->work, process_srcu); ssp->srcu_sup->sda_is_static = is_static; if (!is_static) @@ -1518,8 +1518,8 @@ static void srcu_barrier_cb(struct rcu_head *rhp) sdp = container_of(rhp, struct srcu_data, srcu_barrier_head); ssp = sdp->ssp; - if (atomic_dec_and_test(&ssp->srcu_barrier_cpu_cnt)) - complete(&ssp->srcu_barrier_completion); + if (atomic_dec_and_test(&ssp->srcu_sup->srcu_barrier_cpu_cnt)) + complete(&ssp->srcu_sup->srcu_barrier_completion); } /* @@ -1533,13 +1533,13 @@ static void srcu_barrier_cb(struct rcu_head *rhp) static void srcu_barrier_one_cpu(struct srcu_struct *ssp, struct srcu_data *sdp) { spin_lock_irq_rcu_node(sdp); - atomic_inc(&ssp->srcu_barrier_cpu_cnt); + atomic_inc(&ssp->srcu_sup->srcu_barrier_cpu_cnt); sdp->srcu_barrier_head.func = srcu_barrier_cb; debug_rcu_head_queue(&sdp->srcu_barrier_head); if (!rcu_segcblist_entrain(&sdp->srcu_cblist, &sdp->srcu_barrier_head)) { debug_rcu_head_unqueue(&sdp->srcu_barrier_head); - atomic_dec(&ssp->srcu_barrier_cpu_cnt); + atomic_dec(&ssp->srcu_sup->srcu_barrier_cpu_cnt); } spin_unlock_irq_rcu_node(sdp); } @@ -1552,20 +1552,20 @@ void srcu_barrier(struct srcu_struct *ssp) { int cpu; int idx; - unsigned long s = rcu_seq_snap(&ssp->srcu_barrier_seq); + unsigned long s = rcu_seq_snap(&ssp->srcu_sup->srcu_barrier_seq); check_init_srcu_struct(ssp); - mutex_lock(&ssp->srcu_barrier_mutex); - if (rcu_seq_done(&ssp->srcu_barrier_seq, s)) { + mutex_lock(&ssp->srcu_sup->srcu_barrier_mutex); + if (rcu_seq_done(&ssp->srcu_sup->srcu_barrier_seq, s)) { smp_mb(); /* Force ordering following return. */ - mutex_unlock(&ssp->srcu_barrier_mutex); + mutex_unlock(&ssp->srcu_sup->srcu_barrier_mutex); return; /* Someone else did our work for us. */ } - rcu_seq_start(&ssp->srcu_barrier_seq); - init_completion(&ssp->srcu_barrier_completion); + rcu_seq_start(&ssp->srcu_sup->srcu_barrier_seq); + init_completion(&ssp->srcu_sup->srcu_barrier_completion); /* Initial count prevents reaching zero until all CBs are posted. */ - atomic_set(&ssp->srcu_barrier_cpu_cnt, 1); + atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 1); idx = __srcu_read_lock_nmisafe(ssp); if (smp_load_acquire(&ssp->srcu_sup->srcu_size_state) < SRCU_SIZE_WAIT_BARRIER) @@ -1576,12 +1576,12 @@ void srcu_barrier(struct srcu_struct *ssp) __srcu_read_unlock_nmisafe(ssp, idx); /* Remove the initial count, at which point reaching zero can happen. */ - if (atomic_dec_and_test(&ssp->srcu_barrier_cpu_cnt)) - complete(&ssp->srcu_barrier_completion); - wait_for_completion(&ssp->srcu_barrier_completion); + if (atomic_dec_and_test(&ssp->srcu_sup->srcu_barrier_cpu_cnt)) + complete(&ssp->srcu_sup->srcu_barrier_completion); + wait_for_completion(&ssp->srcu_sup->srcu_barrier_completion); - rcu_seq_end(&ssp->srcu_barrier_seq); - mutex_unlock(&ssp->srcu_barrier_mutex); + rcu_seq_end(&ssp->srcu_sup->srcu_barrier_seq); + mutex_unlock(&ssp->srcu_sup->srcu_barrier_mutex); } EXPORT_SYMBOL_GPL(srcu_barrier);