From nobody Tue Feb 10 04:22:59 2026 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 0A69CC761AF for ; Thu, 30 Mar 2023 22:48:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231348AbjC3WsU (ORCPT ); Thu, 30 Mar 2023 18:48:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42812 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230486AbjC3Wry (ORCPT ); Thu, 30 Mar 2023 18:47:54 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4DE4D113D5; Thu, 30 Mar 2023 15:47:33 -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 DB456B82A62; Thu, 30 Mar 2023 22:47:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 92B33C4339C; Thu, 30 Mar 2023 22:47:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1680216448; bh=73P8AiOczQu3Mui8U57N5Li9dx6JSHAOoEru++2gFoQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LzS8lfvagKkq7ws8iWNcjYvCuVl4wyVlvG9bSUyyvcJd3vJe9bEF5ErGDn+32Jxrb t7u/DuxE+wS9YQyoUNYR6+ql6iE7LveojNtH+pvImJo8BfhEq43FrXThE8mV4vmr6X 5VThIbiNALn4GRiminbhQzzXvtGy8ICguipy/mz/nKbwsamgWsl7Nz+nuoaDTc1gcq xtE4QSrL4+C+muHcBZtQBWHCuI20jGEkpcnt+3yGWn4W25KiUW8Uu14xI3Jhe7NMq1 iTAF03cuAkHaJQ3XEn9YF4PSA/dwillcKnGFjeh2lYF0neSuKHI6oRXEmn36cRIEXQ FZ/ZMD8LgdoLA== Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 0DF5D1540481; Thu, 30 Mar 2023 15:47:28 -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" , Sachin Sant , "Zhang, Qiang1" Subject: [PATCH rcu 05/20] srcu: Move ->level from srcu_struct to srcu_usage Date: Thu, 30 Mar 2023 15:47:11 -0700 Message-Id: <20230330224726.662344-5-paulmck@kernel.org> X-Mailer: git-send-email 2.40.0.rc2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" This commit moves the ->level[] array 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 Tested-by: Sachin Sant Tested-by: "Zhang, Qiang1" Signed-off-by: Paul E. McKenney --- include/linux/srcutree.h | 4 ++-- kernel/rcu/srcutree.c | 14 +++++++------- 2 files changed, 9 insertions(+), 9 deletions(-) diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h index 276f325f1296..c7373fe5c14b 100644 --- a/include/linux/srcutree.h +++ b/include/linux/srcutree.h @@ -62,14 +62,14 @@ struct srcu_node { */ struct srcu_usage { struct srcu_node *node; /* Combining tree. */ + struct srcu_node *level[RCU_NUM_LVLS + 1]; + /* First node at each level. */ }; =20 /* * Per-SRCU-domain structure, similar in function to rcu_state. */ struct srcu_struct { - struct srcu_node *level[RCU_NUM_LVLS + 1]; - /* First node at each level. */ int srcu_size_state; /* Small-to-big transition state. */ struct mutex srcu_cb_mutex; /* Serialize CB preparation. */ spinlock_t __private lock; /* Protect counters and size state. */ diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 049e20dbec76..acb0862faafa 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -178,9 +178,9 @@ static bool init_srcu_struct_nodes(struct srcu_struct *= ssp, gfp_t gfp_flags) return false; =20 /* Work out the overall tree geometry. */ - ssp->level[0] =3D &ssp->srcu_sup->node[0]; + ssp->srcu_sup->level[0] =3D &ssp->srcu_sup->node[0]; for (i =3D 1; i < rcu_num_lvls; i++) - ssp->level[i] =3D ssp->level[i - 1] + num_rcu_lvl[i - 1]; + ssp->srcu_sup->level[i] =3D ssp->srcu_sup->level[i - 1] + num_rcu_lvl[i = - 1]; rcu_init_levelspread(levelspread, num_rcu_lvl); =20 /* Each pass through this loop initializes one srcu_node structure. */ @@ -202,10 +202,10 @@ static bool init_srcu_struct_nodes(struct srcu_struct= *ssp, gfp_t gfp_flags) } =20 /* Non-root node. */ - if (snp =3D=3D ssp->level[level + 1]) + if (snp =3D=3D ssp->srcu_sup->level[level + 1]) level++; - snp->srcu_parent =3D ssp->level[level - 1] + - (snp - ssp->level[level]) / + snp->srcu_parent =3D ssp->srcu_sup->level[level - 1] + + (snp - ssp->srcu_sup->level[level]) / levelspread[level - 1]; } =20 @@ -214,7 +214,7 @@ static bool init_srcu_struct_nodes(struct srcu_struct *= ssp, gfp_t gfp_flags) * leaves of the srcu_node tree. */ level =3D rcu_num_lvls - 1; - snp_first =3D ssp->level[level]; + snp_first =3D ssp->srcu_sup->level[level]; for_each_possible_cpu(cpu) { sdp =3D per_cpu_ptr(ssp->sda, cpu); sdp->mynode =3D &snp_first[cpu / levelspread[level]]; @@ -889,7 +889,7 @@ static void srcu_gp_end(struct srcu_struct *ssp) srcu_for_each_node_breadth_first(ssp, snp) { spin_lock_irq_rcu_node(snp); cbs =3D false; - last_lvl =3D snp >=3D ssp->level[rcu_num_lvls - 1]; + last_lvl =3D snp >=3D ssp->srcu_sup->level[rcu_num_lvls - 1]; if (last_lvl) cbs =3D ss_state < SRCU_SIZE_BIG || snp->srcu_have_cbs[idx] =3D=3D gps= eq; snp->srcu_have_cbs[idx] =3D gpseq; --=20 2.40.0.rc2