From mboxrd@z Thu Jan 1 00:00:00 1970 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 53C9BC433EF for ; Fri, 4 Feb 2022 23:39:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378494AbiBDXjk (ORCPT ); Fri, 4 Feb 2022 18:39:40 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:39388 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378244AbiBDXjH (ORCPT ); Fri, 4 Feb 2022 18:39:07 -0500 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 E157FB83975; Fri, 4 Feb 2022 23:39:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 613EBC340FA; Fri, 4 Feb 2022 23:39:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644017944; bh=nCSQipMnQYydZIPhraT+nyb+OMvwqOwj8Ix07rY+kdY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=V4kMvhyl60zgrjHY7bYaZtCXznXyENURYnxdfo4Er+bbyIqpdDzOkXxfeI4JpwQPW KJl4ENf/51ixYVgXIZTplwD/9BHycOcQyaDOuC5dB/4XNsiTZQ+WI7Oaper4Txa5IM k3ey1mAC8ScItixP4B8b2+qzEHeFt7bUD+Go3mycKbZFIm3UFhmdIzJbeBy+JvIdvr YkXLYLP9TcXFOyBg/rXxLyisuEuIh5Bne1e9EbUYDhwnxwX3Ms3lhnmeoYGFA3/Kli Mrro8Ve7XfLNlHo8R1t5LuzxPuPh9trnzqVq2v+ZAXCsS2Z1H92A+J6o3a4buiforZ ivT/3RDF/96FQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 0166B5C0A6A; Fri, 4 Feb 2022 15:39:03 -0800 (PST) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, rostedt@goodmis.org, "Paul E. McKenney" Subject: [PATCH rcu 08/19] srcu: Add boot-time control over srcu_node array allocation Date: Fri, 4 Feb 2022 15:38:51 -0800 Message-Id: <20220204233902.1902-8-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20220204233858.GA1469@paulmck-ThinkPad-P17-Gen-1> References: <20220204233858.GA1469@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This commit adds an srcu_tree.convert_to_big kernel parameter that either refuses to convert at all (0), converts immediately at init_srcu_struct() time (1), or lets rcutorture convert it (2). An addition contention-based dynamic convertion choice will be added, along with documentation. Signed-off-by: Paul E. McKenney --- kernel/rcu/srcutree.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 550991cc213d3..d1f1ff930acf5 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -39,6 +39,15 @@ module_param(exp_holdoff, ulong, 0444); static ulong counter_wrap_check = (ULONG_MAX >> 2); module_param(counter_wrap_check, ulong, 0444); +/* + * Control conversion to SRCU_SIZE_BIG: + * 0: Don't convert at all (default). + * 1: Convert at init_srcu_struct() time. + * 2: Convert when rcutorture invokes srcu_torture_stats_print(). + */ +static int convert_to_big; +module_param(convert_to_big, int, 0444); + /* Early-boot callback-management, so early that no lock is required! */ static LIST_HEAD(srcu_boot_list); static bool __read_mostly srcu_init_done; @@ -113,7 +122,7 @@ static void init_srcu_struct_data(struct srcu_struct *ssp) * Allocated and initialize SRCU combining tree. Returns @true if * allocation succeeded and @false otherwise. */ -static bool init_srcu_struct_nodes(struct srcu_struct *ssp) +static bool init_srcu_struct_nodes(struct srcu_struct *ssp, gfp_t gfp_flags) { int cpu; int i; @@ -125,7 +134,7 @@ static bool init_srcu_struct_nodes(struct srcu_struct *ssp) /* Initialize geometry if it has not already been initialized. */ rcu_init_geometry(); - ssp->node = kcalloc(rcu_num_nodes, sizeof(*ssp->node), GFP_ATOMIC); + ssp->node = kcalloc(rcu_num_nodes, sizeof(*ssp->node), gfp_flags); if (!ssp->node) return false; @@ -204,6 +213,16 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) init_srcu_struct_data(ssp); ssp->srcu_gp_seq_needed_exp = 0; ssp->srcu_last_gp_end = ktime_get_mono_fast_ns(); + if (READ_ONCE(ssp->srcu_size_state) == SRCU_SIZE_SMALL && convert_to_big == 1) { + if (!init_srcu_struct_nodes(ssp, GFP_ATOMIC)) { + if (!is_static) { + free_percpu(ssp->sda); + ssp->sda = NULL; + } + return -ENOMEM; + } + WRITE_ONCE(ssp->srcu_size_state, SRCU_SIZE_BIG); + } smp_store_release(&ssp->srcu_gp_seq_needed, 0); /* Init done. */ return 0; } @@ -627,7 +646,7 @@ static void srcu_gp_end(struct srcu_struct *ssp) ss_state = smp_load_acquire(&ssp->srcu_size_state); if (ss_state && ss_state != SRCU_SIZE_BIG) { if (ss_state == SRCU_SIZE_ALLOC) - init_srcu_struct_nodes(ssp); + init_srcu_struct_nodes(ssp, GFP_KERNEL); else smp_store_release(&ssp->srcu_size_state, ss_state + 1); } @@ -1456,6 +1475,8 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf) s1 += c1; } pr_cont(" T(%ld,%ld)\n", s0, s1); + if (READ_ONCE(ssp->srcu_size_state) == SRCU_SIZE_SMALL && convert_to_big == 2) + WRITE_ONCE(ssp->srcu_size_state, SRCU_SIZE_ALLOC); } EXPORT_SYMBOL_GPL(srcu_torture_stats_print); -- 2.31.1.189.g2e36527f23