From patchwork Fri Jul 28 10:00:46 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Rafael J. Wysocki" X-Patchwork-Id: 707874 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 28B19C001DE for ; Fri, 28 Jul 2023 10:02:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235252AbjG1KCv (ORCPT ); Fri, 28 Jul 2023 06:02:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37192 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235349AbjG1KC3 (ORCPT ); Fri, 28 Jul 2023 06:02:29 -0400 Received: from cloudserver094114.home.pl (cloudserver094114.home.pl [79.96.170.134]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2AE0149CA; Fri, 28 Jul 2023 03:01:59 -0700 (PDT) Received: from localhost (127.0.0.1) (HELO v370.home.net.pl) by /usr/run/smtp (/usr/run/postfix/private/idea_relay_lmtp) via UNIX with SMTP (IdeaSmtpServer 5.2.0) id da2d6a680178221d; Fri, 28 Jul 2023 12:01:57 +0200 Authentication-Results: v370.home.net.pl; spf=softfail (domain owner discourages use of this host) smtp.mailfrom=rjwysocki.net (client-ip=195.136.19.94; helo=[195.136.19.94]; envelope-from=rjw@rjwysocki.net; receiver=) Received: from kreacher.localnet (unknown [195.136.19.94]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by v370.home.net.pl (Postfix) with ESMTPSA id 0B801661E3D; Fri, 28 Jul 2023 12:01:57 +0200 (CEST) From: "Rafael J. Wysocki" To: Linux PM Cc: LKML , Peter Zijlstra , Anna-Maria Behnsen , Frederic Weisbecker , Kajetan Puchalski Subject: [PATCH v2 2/3] cpuidle: teo: Avoid stopping the tick unnecessarily when bailing out Date: Fri, 28 Jul 2023 12:00:46 +0200 Message-ID: <3254124.aeNJFYEL58@kreacher> In-Reply-To: <5707588.DvuYhMxLoT@kreacher> References: <5707588.DvuYhMxLoT@kreacher> MIME-Version: 1.0 X-CLIENT-IP: 195.136.19.94 X-CLIENT-HOSTNAME: 195.136.19.94 X-VADE-SPAMSTATE: clean X-VADE-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedviedrieeigddvtdcutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfjqffogffrnfdpggftiffpkfenuceurghilhhouhhtmecuudehtdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhephffvvefufffkjghfggfgtgesthfuredttddtjeenucfhrhhomhepfdftrghfrggvlhculfdrucghhihsohgtkhhifdcuoehrjhifsehrjhifhihsohgtkhhirdhnvghtqeenucggtffrrghtthgvrhhnpedvffeuiedtgfdvtddugeeujedtffetteegfeekffdvfedttddtuefhgeefvdejhfenucfkphepudelhedrudefiedrudelrdelgeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpeduleehrddufeeirdduledrleegpdhhvghlohepkhhrvggrtghhvghrrdhlohgtrghlnhgvthdpmhgrihhlfhhrohhmpedftfgrfhgrvghlucflrdcuhgihshhotghkihdfuceorhhjfiesrhhjfiihshhotghkihdrnhgvtheqpdhnsggprhgtphhtthhopeeipdhrtghpthhtoheplhhinhhugidqphhmsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtoheplhhinhhugidqkhgvrhhnvghlsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtohepphgvthgvrhiisehinhhfrhgruggvrggurdhorhhgpdhrtghpthhtoheprghnnhgrqdhmrghrihgrsehlihhnuhhtrhhonhhigidruggvpdhrtghpthhtohepfhhrvggu vghrihgtsehkvghrnhgvlhdrohhrghdprhgtphhtthhopehkrghjvghtrghnrdhpuhgthhgrlhhskhhisegrrhhmrdgtohhm X-DCC--Metrics: v370.home.net.pl 1024; Body=6 Fuz1=6 Fuz2=6 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org From: Rafael J. Wysocki When teo_select() is going to return early in some special cases, make it avoid stopping the tick if the idle state to be returned is shallow. Signed-off-by: Rafael J. Wysocki --- drivers/cpuidle/governors/teo.c | 50 +++++++++++++++++++++++++--------------- 1 file changed, 32 insertions(+), 18 deletions(-) Index: linux-pm/drivers/cpuidle/governors/teo.c =================================================================== --- linux-pm.orig/drivers/cpuidle/governors/teo.c +++ linux-pm/drivers/cpuidle/governors/teo.c @@ -462,9 +462,9 @@ static int teo_select(struct cpuidle_dri /* Avoid unnecessary overhead. */ if (idx < 0) { idx = 0; /* No states enabled, must use 0. */ - goto end; + goto bail_out; } else if (idx == idx0) { - goto end; + goto bail_out; } /* @@ -547,8 +547,10 @@ static int teo_select(struct cpuidle_dri * If there is a latency constraint, it may be necessary to select an * idle state shallower than the current candidate one. */ - if (idx > constraint_idx) + if (idx > constraint_idx) { idx = constraint_idx; + goto bail_out; + } /* * If the CPU is being utilized over the threshold, choose a shallower @@ -569,23 +571,35 @@ static int teo_select(struct cpuidle_dri end: /* - * Don't stop the tick if the selected state is a polling one or if the - * expected idle duration is shorter than the tick period length. + * Allow the tick to be stopped unless the selected state is a polling + * one or the expected idle duration is shorter than the tick period + * length. */ - if (((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) || - duration_ns < TICK_NSEC) && !tick_nohz_tick_stopped()) { - *stop_tick = false; + if ((!(drv->states[idx].flags & CPUIDLE_FLAG_POLLING) && + duration_ns >= TICK_NSEC) || tick_nohz_tick_stopped()) + return idx; - /* - * The tick is not going to be stopped, so if the target - * residency of the state to be returned is not within the time - * till the closest timer including the tick, try to correct - * that. - */ - if (idx > idx0 && - drv->states[idx].target_residency_ns > delta_tick) - idx = teo_find_shallower_state(drv, dev, idx, delta_tick, false); - } +retain_tick: + *stop_tick = false; + + /* + * The tick is not going to be stopped, so if the target residency of + * the state to be returned is not within the time till the closest + * timer including the tick, try to correct that. + */ + if (idx > idx0 && + drv->states[idx].target_residency_ns > delta_tick) + idx = teo_find_shallower_state(drv, dev, idx, delta_tick, false); + + return idx; + +bail_out: + /* + * Do not allow the tick to be stopped if the selected state is shallow + * enough. + */ + if (drv->states[idx].target_residency_ns < TICK_NSEC) + goto retain_tick; return idx; }