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=-16.7 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 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 6E427C4338F for ; Wed, 28 Jul 2021 17:38:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E6506101E for ; Wed, 28 Jul 2021 17:38:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229603AbhG1Rib (ORCPT ); Wed, 28 Jul 2021 13:38:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:58964 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229581AbhG1Rib (ORCPT ); Wed, 28 Jul 2021 13:38:31 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3A7506103E; Wed, 28 Jul 2021 17:38:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627493909; bh=xW/pDu1zJLsRdhipPxhrV+TMxZ+TgZXD4N6tQJtcRfE=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=tB6/5VSbif3jvDBNCRmmaMrwytQnX4Yoyu7LygD2P45NkLzXR8JzTkBj6JUkrQoxO rjO/VFLmXeFPBt0uHYsTyyptmi89PQngkYXBBYeZBBCFqseHWBNC7pIwpTFDl6cuJN Stwi+Um+293x65fsT67HkXzlsoYhfkoRgzBAC8gQowiPwBff5cSBniwgJt3UaA+Jjy kj+7PmthhN9T7eovbtErsfZBwuBIiBwQaY6Ehx71CMURnMuSSFllOW+lOyGA4jcUVw Ly2Um+eUf9WCgB7kEP1NcaiVukHqDky08VcBivd7N+KHO527gygAg5ylq67pg5hIKz uU7G7kr3ZVSng== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 07E015C048D; Wed, 28 Jul 2021 10:38:29 -0700 (PDT) Date: Wed, 28 Jul 2021 10:38:29 -0700 From: "Paul E. McKenney" 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 Subject: [PATCH v2 rcu 1/7] refscale: Add measurement of clock readout Message-ID: <20210728173829.GB9416@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org References: <20210721210421.GA788053@paulmck-ThinkPad-P17-Gen-1> <20210721210441.796995-1-paulmck@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210721210441.796995-1-paulmck@kernel.org> Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org This commit adds a "clock" type to refscale, which checks the performance of ktime_get_real_fast_ns(). Use the "clocksource=" kernel boot parameter to select the underlying clock source. [ paulmck: Work around compiler false positive per kernel test robot. ] Signed-off-by: Paul E. McKenney diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c index d998a76fb5422..66dc14cf5687e 100644 --- a/kernel/rcu/refscale.c +++ b/kernel/rcu/refscale.c @@ -467,6 +467,40 @@ static struct ref_scale_ops acqrel_ops = { .name = "acqrel" }; +static volatile u64 stopopts; + +static void ref_clock_section(const int nloops) +{ + u64 x = 0; + int i; + + preempt_disable(); + for (i = nloops; i >= 0; i--) + x += ktime_get_real_fast_ns(); + preempt_enable(); + stopopts = x; +} + +static void ref_clock_delay_section(const int nloops, const int udl, const int ndl) +{ + u64 x = 0; + int i; + + preempt_disable(); + for (i = nloops; i >= 0; i--) { + x += ktime_get_real_fast_ns(); + un_delay(udl, ndl); + } + preempt_enable(); + stopopts = x; +} + +static struct ref_scale_ops clock_ops = { + .readsection = ref_clock_section, + .delaysection = ref_clock_delay_section, + .name = "clock" +}; + static void rcu_scale_one_reader(void) { if (readdelay <= 0) @@ -759,7 +793,7 @@ ref_scale_init(void) int firsterr = 0; static struct ref_scale_ops *scale_ops[] = { &rcu_ops, &srcu_ops, &rcu_trace_ops, &rcu_tasks_ops, &refcnt_ops, &rwlock_ops, - &rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops, + &rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops, &clock_ops, }; if (!torture_init_begin(scale_type, verbose))