From patchwork Mon Jul 17 18:10:06 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: 13316175 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 D8F15EB64DC for ; Mon, 17 Jul 2023 18:10:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229630AbjGQSKL (ORCPT ); Mon, 17 Jul 2023 14:10:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40776 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230128AbjGQSKK (ORCPT ); Mon, 17 Jul 2023 14:10:10 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 52EE6E55; Mon, 17 Jul 2023 11:10:09 -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 D56B4611D5; Mon, 17 Jul 2023 18:10:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 419A6C433CB; Mon, 17 Jul 2023 18:10:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689617408; bh=9DECvy9XfdgRY+x9LckD1Cegiv8FGc1KYWwYrCtIolA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uQ20wt8hXUnilQK44b7T3ETV6YhnGxFIP2ItWK0ReN+Zb2YZlIDPq60bkKEStAXae SehDce8e8mztDJ3zyMNhgIKie5LnJtmimW0pig1upIknxQq6JejG0ModyG3B/I7RMZ +Om3p/UisF3Y0+hg4LVyoelXGyghl171Kyss58KU1iIWY1nI6aCDY6jeyhAe6kbXoV /+KGKXgxJ84EP8pcGZ0V5rGafu9ubEEC7WfXMbiz/zQeH/CNshuGzRPA/BV6zcEx12 xBZgTXwj4TzdH1FcTtzHbYvjLLXqveMUXz3CjyaJNwDTUUCL+ZvrEFzMrWTz/ZbpCt ZRrrQtWnUxhXg== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id D45E7CE0806; Mon, 17 Jul 2023 11:10:07 -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" Subject: [PATCH rcu 3/3] refscale: Add a "jiffies" test Date: Mon, 17 Jul 2023 11:10:06 -0700 Message-Id: <20230717181006.1097957-3-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <2c4aea8b-6f82-45ab-988e-a6bb19129808@paulmck-laptop> References: <2c4aea8b-6f82-45ab-988e-a6bb19129808@paulmck-laptop> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org This commit adds a "jiffies" test to refscale, allowing use of jiffies to be compared to ktime_get_real_fast_ns(). On my x86 laptop, jiffies is more than 20x faster. (Though for many uses, the tens-of-nanoseconds overhead of ktime_get_real_fast_ns() will be just fine.) Signed-off-by: Paul E. McKenney --- kernel/rcu/refscale.c | 34 +++++++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c index 71d138573856..91a0fd0d4d9a 100644 --- a/kernel/rcu/refscale.c +++ b/kernel/rcu/refscale.c @@ -528,6 +528,38 @@ static struct ref_scale_ops clock_ops = { .name = "clock" }; +static void ref_jiffies_section(const int nloops) +{ + u64 x = 0; + int i; + + preempt_disable(); + for (i = nloops; i >= 0; i--) + x += jiffies; + preempt_enable(); + stopopts = x; +} + +static void ref_jiffies_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 += jiffies; + un_delay(udl, ndl); + } + preempt_enable(); + stopopts = x; +} + +static struct ref_scale_ops jiffies_ops = { + .readsection = ref_jiffies_section, + .delaysection = ref_jiffies_delay_section, + .name = "jiffies" +}; + //////////////////////////////////////////////////////////////////////// // // Methods leveraging SLAB_TYPESAFE_BY_RCU. @@ -1047,7 +1079,7 @@ 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, &clock_ops, + &rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops, &clock_ops, &jiffies_ops, &typesafe_ref_ops, &typesafe_lock_ops, &typesafe_seqlock_ops, };