Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964908AbbELWfu (ORCPT ); Tue, 12 May 2015 18:35:50 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:60708 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933943AbbELWbG (ORCPT ); Tue, 12 May 2015 18:31:06 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 17/24] rcu: Enable diagnostic dump of rcu_node combining tree Date: Tue, 12 May 2015 15:30:47 -0700 Message-Id: <1431469854-3826-17-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.5 In-Reply-To: <1431469854-3826-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20150512223034.GA1396@linux.vnet.ibm.com> <1431469854-3826-1-git-send-email-paulmck@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15051222-0013-0000-0000-00000AB42532 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3064 Lines: 90 From: "Paul E. McKenney" The purpose of this commit is to make it easier to verify that RCU's combining tree is set up correctly, which is useful to have when making changes in how that tree is initialized. Signed-off-by: Paul E. McKenney Reviewed-by: Pranith Kumar [ paulmck: Fold fix found by Fengguang's 0-day test robot. ] --- Documentation/kernel-parameters.txt | 5 +++++ kernel/rcu/tree.c | 27 +++++++++++++++++++++++++++ 2 files changed, 32 insertions(+) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 73ac8aa84608..5a8d9f7a66fe 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2992,6 +2992,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Set maximum number of finished RCU callbacks to process in one batch. + rcutree.dump_tree= [KNL] + Dump the structure of the rcu_node combining tree + out at early boot. This is used for diagnostic + purposes, to verify correct tree setup. + rcutree.gp_cleanup_delay= [KNL] Set the number of jiffies to delay each step of RCU grace-period cleanup. This only has effect diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 227b4f2cfb1e..01719402fe8e 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -113,6 +113,9 @@ RCU_STATE_INITIALIZER(rcu_bh, 'b', call_rcu_bh); static struct rcu_state *rcu_state_p; LIST_HEAD(rcu_struct_flavors); +/* Dump rcu_node combining tree at boot to verify correct setup. */ +static bool dump_tree; +module_param(dump_tree, bool, 0444); /* Control rcu_node-tree auto-balancing at boot time. */ static bool rcu_fanout_exact; module_param(rcu_fanout_exact, bool, 0444); @@ -4131,6 +4134,28 @@ static void __init rcu_init_geometry(void) rcu_num_nodes += num_rcu_lvl[i]; } +/* + * Dump out the structure of the rcu_node combining tree associated + * with the rcu_state structure referenced by rsp. + */ +static void __init rcu_dump_rcu_node_tree(struct rcu_state *rsp) +{ + int level = 0; + struct rcu_node *rnp; + + pr_info("rcu_node tree layout dump\n"); + pr_info(" "); + rcu_for_each_node_breadth_first(rsp, rnp) { + if (rnp->level != level) { + pr_cont("\n"); + pr_info(" "); + level = rnp->level; + } + pr_cont("%d:%d ^%d ", rnp->grplo, rnp->grphi, rnp->grpnum); + } + pr_cont("\n"); +} + void __init rcu_init(void) { int cpu; @@ -4141,6 +4166,8 @@ void __init rcu_init(void) rcu_init_geometry(); rcu_init_one(&rcu_bh_state, &rcu_bh_data); rcu_init_one(&rcu_sched_state, &rcu_sched_data); + if (dump_tree) + rcu_dump_rcu_node_tree(&rcu_sched_state); __rcu_init_preempt(); open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); -- 1.8.1.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/