From patchwork Mon Jul 17 18:11:31 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: 13316224 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 36019C001E0 for ; Mon, 17 Jul 2023 18:11:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231283AbjGQSLq (ORCPT ); Mon, 17 Jul 2023 14:11:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42214 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230505AbjGQSLn (ORCPT ); Mon, 17 Jul 2023 14:11:43 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 382DD8E; Mon, 17 Jul 2023 11:11:42 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2341B611E4; Mon, 17 Jul 2023 18:11:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4D6EAC433AD; Mon, 17 Jul 2023 18:11:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689617500; bh=MIhkeztsVEuhvwr2MszSXvW/fHdP74ZIBpgGzjKJOiI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ESE4wom7KKaNW9leiHXoMJj7L0T+MzWGD5OkIzc64KKMmdDl2S8BaLZ0gkas26IWv LUY2EYq2hYp6TFC3lzbhVniZmDfAJ1iMCH4lOzBLurSnrX4Sj8Uv09PlOOhdu4vU/m EKUV5Mo+YKDz3ScEWvDirSmjJbpeNWraepE0TxU947n73KC2CcuMETZDbQIJwzMjHZ gvX8s9oKlHGvRjBVC+ZnTJbJEzTxBSJBTP85411UzR/b2cyx2UilK2t6jISodbky8D cvBtpcvCEhyGThcxpko2XfW4/AzE0xds15W184m/HtfVwY49BFtGhXMv1Cy6DR2yQA 9ox0Xw/6FW4gQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id B9A28CE092F; Mon, 17 Jul 2023 11:11:39 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, "Paul E. McKenney" , Yujie Liu Subject: [PATCH rcu 06/13] rcuscale: Measure grace-period kthread CPU time Date: Mon, 17 Jul 2023 11:11:31 -0700 Message-Id: <20230717181138.1098063-6-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org This commit adds the ability to output the CPU time consumed by the grace-period kthread for the RCU variant under test. The CPU time is whatever is in the designated task's current->stime field, and thus is controlled by whatever CPU-time accounting scheme is in effect. This output appears in microseconds as follows on the console: rcu_scale: Grace-period kthread CPU time: 42367.037 [ paulmck: Apply feedback from Stephen Rothwell and kernel test robot. ] Signed-off-by: Paul E. McKenney Tested-by: Yujie Liu --- include/linux/rcupdate_trace.h | 1 + kernel/rcu/rcuscale.c | 21 +++++++++++++++++++++ kernel/rcu/tasks.h | 6 ++++++ 3 files changed, 28 insertions(+) diff --git a/include/linux/rcupdate_trace.h b/include/linux/rcupdate_trace.h index 9bc8cbb33340..eda493200663 100644 --- a/include/linux/rcupdate_trace.h +++ b/include/linux/rcupdate_trace.h @@ -87,6 +87,7 @@ static inline void rcu_read_unlock_trace(void) void call_rcu_tasks_trace(struct rcu_head *rhp, rcu_callback_t func); void synchronize_rcu_tasks_trace(void); void rcu_barrier_tasks_trace(void); +struct task_struct *get_rcu_tasks_trace_gp_kthread(void); #else /* * The BPF JIT forms these addresses even when it doesn't call these diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c index 821a3e65c54a..7fba3ab66e35 100644 --- a/kernel/rcu/rcuscale.c +++ b/kernel/rcu/rcuscale.c @@ -141,6 +141,7 @@ struct rcu_scale_ops { void (*gp_barrier)(void); void (*sync)(void); void (*exp_sync)(void); + struct task_struct *(*rso_gp_kthread)(void); const char *name; }; @@ -336,6 +337,7 @@ static struct rcu_scale_ops tasks_tracing_ops = { .gp_barrier = rcu_barrier_tasks_trace, .sync = synchronize_rcu_tasks_trace, .exp_sync = synchronize_rcu_tasks_trace, + .rso_gp_kthread = get_rcu_tasks_trace_gp_kthread, .name = "tasks-tracing" }; @@ -563,6 +565,8 @@ static struct task_struct **kfree_reader_tasks; static int kfree_nrealthreads; static atomic_t n_kfree_scale_thread_started; static atomic_t n_kfree_scale_thread_ended; +static struct task_struct *kthread_tp; +static u64 kthread_stime; struct kfree_obj { char kfree_obj[8]; @@ -808,6 +812,18 @@ rcu_scale_cleanup(void) if (gp_exp && gp_async) SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!"); + // If built-in, just report all of the GP kthread's CPU time. + if (IS_BUILTIN(CONFIG_RCU_SCALE_TEST) && !kthread_tp && cur_ops->rso_gp_kthread) + kthread_tp = cur_ops->rso_gp_kthread(); + if (kthread_tp) { + u32 ns; + u64 us; + + kthread_stime = kthread_tp->stime - kthread_stime; + us = div_u64_rem(kthread_stime, 1000, &ns); + pr_info("rcu_scale: Grace-period kthread CPU time: %llu.%03u us\n", us, ns); + show_rcu_gp_kthreads(); + } if (kfree_rcu_test) { kfree_scale_cleanup(); return; @@ -921,6 +937,11 @@ rcu_scale_init(void) if (cur_ops->init) cur_ops->init(); + if (cur_ops->rso_gp_kthread) { + kthread_tp = cur_ops->rso_gp_kthread(); + if (kthread_tp) + kthread_stime = kthread_tp->stime; + } if (kfree_rcu_test) return kfree_scale_init(); diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index b770add3f843..990a6cf5fa35 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -1830,6 +1830,12 @@ void show_rcu_tasks_trace_gp_kthread(void) EXPORT_SYMBOL_GPL(show_rcu_tasks_trace_gp_kthread); #endif // !defined(CONFIG_TINY_RCU) +struct task_struct *get_rcu_tasks_trace_gp_kthread(void) +{ + return rcu_tasks_trace.kthread_ptr; +} +EXPORT_SYMBOL_GPL(get_rcu_tasks_trace_gp_kthread); + #else /* #ifdef CONFIG_TASKS_TRACE_RCU */ static void exit_tasks_rcu_finish_trace(struct task_struct *t) { } #endif /* #else #ifdef CONFIG_TASKS_TRACE_RCU */