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 X-Spam-Level: X-Spam-Status: No, score=-19.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1244CC433E6 for ; Wed, 6 Jan 2021 17:18:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BA19722227 for ; Wed, 6 Jan 2021 17:18:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727733AbhAFRRx (ORCPT ); Wed, 6 Jan 2021 12:17:53 -0500 Received: from mail.kernel.org ([198.145.29.99]:60354 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727645AbhAFRRx (ORCPT ); Wed, 6 Jan 2021 12:17:53 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8E40823132; Wed, 6 Jan 2021 17:17:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1609953432; bh=aO51+nFL0aN+LRSsFz74vIhhXFFoO6tkeT1fWqEziII=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=obh9cob/rQlCTayzMYa+PH683N0jebdtI9lLO4JjmKoJY97B1vJjzHv6IRIjRvfly WxLyuFZWcijXMSqr44SZxoT1VMwzXcaKKFVwDMVV9IwzuQUnOEXRDIYSEVuhaou0IV idpFS9rr/0H9dgHe2X4YWhziz4uB2eDZbTpZ3bY/V7ZqK/lU4LBsXe31JdEy4wjf82 wSnV8NivMHTMZx8KtUicck1g/4YsinbJMj7mwV9sgx/2dnd/DmBXe06Dcj9ArSv9g/ CcGdoEdIMhkYz7fx/CjoZCT8t6IgTd1GilbDkDZDGY0YwAIhdRg9EZv8AJrsuNEIaV dR6Lodib+INYg== From: paulmck@kernel.org To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.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, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 03/17] refscale: Allow summarization of verbose output Date: Wed, 6 Jan 2021 09:16:56 -0800 Message-Id: <20210106171710.22239-3-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20210106171532.GA20769@paulmck-ThinkPad-P72> References: <20210106171532.GA20769@paulmck-ThinkPad-P72> Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org From: "Paul E. McKenney" The refscale test prints enough per-kthread console output to provoke RCU CPU stall warnings on large systems. This commit therefore allows this output to be summarized. For example, the refscale.verbose_batched=32 boot parameter would causes only every 32nd line of output to be logged. Signed-off-by: Paul E. McKenney --- Documentation/admin-guide/kernel-parameters.txt | 6 ++++++ kernel/rcu/refscale.c | 21 ++++++++++++++++----- 2 files changed, 22 insertions(+), 5 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index c722ec1..29ea816 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4557,6 +4557,12 @@ refscale.verbose= [KNL] Enable additional printk() statements. + refscale.verbose_batched= [KNL] + Batch the additional printk() statements. If zero + (the default) or negative, print everything. Otherwise, + print every Nth verbose statement, where N is the value + specified. + relax_domain_level= [KNL, SMP] Set scheduler's default relax_domain_level. See Documentation/admin-guide/cgroup-v1/cpusets.rst. diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c index 23ff36a..3da246f 100644 --- a/kernel/rcu/refscale.c +++ b/kernel/rcu/refscale.c @@ -46,6 +46,16 @@ #define VERBOSE_SCALEOUT(s, x...) \ do { if (verbose) pr_alert("%s" SCALE_FLAG s, scale_type, ## x); } while (0) +static atomic_t verbose_batch_ctr; + +#define VERBOSE_SCALEOUT_BATCH(s, x...) \ +do { \ + if (verbose && \ + (verbose_batched <= 0 || \ + !(atomic_inc_return(&verbose_batch_ctr) % verbose_batched))) \ + pr_alert("%s" SCALE_FLAG s, scale_type, ## x); \ +} while (0) + #define VERBOSE_SCALEOUT_ERRSTRING(s, x...) \ do { if (verbose) pr_alert("%s" SCALE_FLAG "!!! " s, scale_type, ## x); } while (0) @@ -57,6 +67,7 @@ module_param(scale_type, charp, 0444); MODULE_PARM_DESC(scale_type, "Type of test (rcu, srcu, refcnt, rwsem, rwlock."); torture_param(int, verbose, 0, "Enable verbose debugging printk()s"); +torture_param(int, verbose_batched, 0, "Batch verbose debugging printk()s"); // Wait until there are multiple CPUs before starting test. torture_param(int, holdoff, IS_BUILTIN(CONFIG_RCU_REF_SCALE_TEST) ? 10 : 0, @@ -368,14 +379,14 @@ ref_scale_reader(void *arg) u64 start; s64 duration; - VERBOSE_SCALEOUT("ref_scale_reader %ld: task started", me); + VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: task started", me); set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids)); set_user_nice(current, MAX_NICE); atomic_inc(&n_init); if (holdoff) schedule_timeout_interruptible(holdoff * HZ); repeat: - VERBOSE_SCALEOUT("ref_scale_reader %ld: waiting to start next experiment on cpu %d", me, smp_processor_id()); + VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: waiting to start next experiment on cpu %d", me, smp_processor_id()); // Wait for signal that this reader can start. wait_event(rt->wq, (atomic_read(&nreaders_exp) && smp_load_acquire(&rt->start_reader)) || @@ -392,7 +403,7 @@ ref_scale_reader(void *arg) while (atomic_read_acquire(&n_started)) cpu_relax(); - VERBOSE_SCALEOUT("ref_scale_reader %ld: experiment %d started", me, exp_idx); + VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: experiment %d started", me, exp_idx); // To reduce noise, do an initial cache-warming invocation, check @@ -421,8 +432,8 @@ ref_scale_reader(void *arg) if (atomic_dec_and_test(&nreaders_exp)) wake_up(&main_wq); - VERBOSE_SCALEOUT("ref_scale_reader %ld: experiment %d ended, (readers remaining=%d)", - me, exp_idx, atomic_read(&nreaders_exp)); + VERBOSE_SCALEOUT_BATCH("ref_scale_reader %ld: experiment %d ended, (readers remaining=%d)", + me, exp_idx, atomic_read(&nreaders_exp)); if (!torture_must_stop()) goto repeat; -- 2.9.5