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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 E8F03C2D0BF for ; Mon, 16 Dec 2019 18:25:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C2A812082E for ; Mon, 16 Dec 2019 18:25:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576520701; bh=HfD4S4urxDR+cnXAVaoUFQrTjdrr5ccm1GZYo4sdWo8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=YrOESOTakzwj4CFaYbq30+RGD8FSm2thjjWzfjx3YQszpn0XhNHo41PYBLevyZaRC bW7dQYn/prWayS2TjToBS385C3tZsPNrLD0lwH+NQzt36pYUsPHCFyz5NNDvSe1Und 35Fabjnrh6VrzPbkJS44g3x09sc7PwTxB0GXyU6I= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731900AbfLPSY5 (ORCPT ); Mon, 16 Dec 2019 13:24:57 -0500 Received: from mail.kernel.org ([198.145.29.99]:45046 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731568AbfLPSSp (ORCPT ); Mon, 16 Dec 2019 13:18:45 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AE1AE2082E; Mon, 16 Dec 2019 18:18:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576520325; bh=HfD4S4urxDR+cnXAVaoUFQrTjdrr5ccm1GZYo4sdWo8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JFhdQ/2uP4cgkdawajs7N6902V2LGotOW4iWzF9lrdZoUnJaigt4J1TM1asOzl88B ENL6w8i1iuZZw4x4TVdyobk57tnn14U+emVcDjgqoLHNA7uCRvjnwJ6id164llMri3 d23fUb8+ALtQ+KfH6vWF5L4lSyysQrMnJq9lkGEg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Doug Smythies , "Rafael J. Wysocki" Subject: [PATCH 5.4 108/177] cpuidle: teo: Fix "early hits" handling for disabled idle states Date: Mon, 16 Dec 2019 18:49:24 +0100 Message-Id: <20191216174841.784914948@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191216174811.158424118@linuxfoundation.org> References: <20191216174811.158424118@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Rafael J. Wysocki commit 159e48560f51d9c2aa02d762a18cd24f7868ab27 upstream. The TEO governor uses idle duration "bins" defined in accordance with the CPU idle states table provided by the driver, so that each "bin" covers the idle duration range between the target residency of the idle state corresponding to it and the target residency of the closest deeper idle state. The governor collects statistics for each bin regardless of whether or not the idle state corresponding to it is currently enabled. In particular, the "early hits" metric measures the likelihood of a situation in which the idle duration measured after wakeup falls into to given bin, but the time till the next timer (sleep length) falls into a bin corresponding to one of the deeper idle states. It is used when the "hits" and "misses" metrics indicate that the state "matching" the sleep length should not be selected, so that the state with the maximum "early hits" value is selected instead of it. If the idle state corresponding to the given bin is disabled, it cannot be selected and if it turns out to be the one that should be selected, a shallower idle state needs to be used instead of it. Nevertheless, the metrics collected for the bin corresponding to it are still valid and need to be taken into account as though that state had not been disabled. As far as the "early hits" metric is concerned, teo_select() tries to take disabled states into account, but the state index corresponding to the maximum "early hits" value computed by it may be incorrect. Namely, it always uses the index of the previous maximum "early hits" state then, but there may be enabled idle states closer to the disabled one in question. In particular, if the current candidate state (whose index is the idx value) is closer to the disabled one and the "early hits" value of the disabled state is greater than the current maximum, the index of the current candidate state (idx) should replace the "maximum early hits state" index. Modify the code to handle that case correctly. Fixes: b26bf6ab716f ("cpuidle: New timer events oriented governor for tickless systems") Reported-by: Doug Smythies Signed-off-by: Rafael J. Wysocki Cc: 5.1+ # 5.1+ Signed-off-by: Greg Kroah-Hartman --- drivers/cpuidle/governors/teo.c | 35 ++++++++++++++++++++++++++--------- 1 file changed, 26 insertions(+), 9 deletions(-) --- a/drivers/cpuidle/governors/teo.c +++ b/drivers/cpuidle/governors/teo.c @@ -277,18 +277,35 @@ static int teo_select(struct cpuidle_dri hits = cpu_data->states[i].hits; misses = cpu_data->states[i].misses; + if (early_hits >= cpu_data->states[i].early_hits || + idx < 0) + continue; + + /* + * If the current candidate state has been the one with + * the maximum "early hits" metric so far, the "early + * hits" metric of the disabled state replaces the + * current "early hits" count to avoid selecting a + * deeper state with lower "early hits" metric. + */ + if (max_early_idx == idx) { + early_hits = cpu_data->states[i].early_hits; + continue; + } + /* - * If the "early hits" metric of a disabled state is - * greater than the current maximum, it should be taken - * into account, because it would be a mistake to select - * a deeper state with lower "early hits" metric. The - * index cannot be changed to point to it, however, so - * just increase the "early hits" count alone and let - * the index still point to a shallower idle state. + * The current candidate state is closer to the disabled + * one than the current maximum "early hits" state, so + * replace the latter with it, but in case the maximum + * "early hits" state index has not been set so far, + * check if the current candidate state is not too + * shallow for that role. */ - if (max_early_idx >= 0 && - early_hits < cpu_data->states[i].early_hits) + if (!(tick_nohz_tick_stopped() && + drv->states[idx].target_residency < TICK_USEC)) { early_hits = cpu_data->states[i].early_hits; + max_early_idx = idx; + } continue; }