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=-20.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 DF0F2C49361 for ; Mon, 28 Jun 2021 13:58:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C9FD461C75 for ; Mon, 28 Jun 2021 13:58:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232357AbhF1OAq (ORCPT ); Mon, 28 Jun 2021 10:00:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57442 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232311AbhF1OAd (ORCPT ); Mon, 28 Jun 2021 10:00:33 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AEDC7C061574; Mon, 28 Jun 2021 06:58:07 -0700 (PDT) Date: Mon, 28 Jun 2021 13:58:05 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1624888686; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EA49D6jjvfTlGevWpnlR1iszrSoWl6SMVQnnoJ7fGqw=; b=UJnMJ2MA7/SKmCq87VvNM1jwi/VKXr79u6gdEc/5C/o3fQqvERmxC5QOAhkhvGIYfnYRAp Dc6xpMBHe7d7wkxlPrPSo+Uu/tCY/HUrj36gwF25bm5BAcAQRcqKoscPrLOybEXvnDJ7Je fPTmPlZG1TRv12NrEyvAhDN2JnFqoEFDCb+7ykfjEm5jHOIWFEU3Hd85oCU3+sHCjSNiHG XOVPxFg9lLYnix1WKcXsKsiQHb5eAERwRJZRMsltyGg5LXasRq3u+rsZmQoBubKysnkEPo +PWFVLIq4htdDN2OzAoaLFAusZGGi4lkiy8M+0EbfMA12CL+zfVkGvC5JkWvaw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1624888686; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EA49D6jjvfTlGevWpnlR1iszrSoWl6SMVQnnoJ7fGqw=; b=1JLBBZm+UfIKDwE2LUJCd2szVYD4eF9xsdXPtij4IMjkAniNKbQth94KP8e5IK1Mbg8OCh qYPuuVyxp1VZ4gCg== From: "tip-bot2 for Odin Ugedal" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] sched/fair: Ensure _sum and _avg values stay consistent Cc: Sachin Sant , Naresh Kamboju , Odin Ugedal , "Peter Zijlstra (Intel)" , Vincent Guittot , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20210624111815.57937-1-odin@uged.al> References: <20210624111815.57937-1-odin@uged.al> MIME-Version: 1.0 Message-ID: <162488868552.395.3605721602918699622.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/core branch of tip: Commit-ID: 1c35b07e6d3986474e5635be566e7bc79d97c64d Gitweb: https://git.kernel.org/tip/1c35b07e6d3986474e5635be566e7bc79d97c64d Author: Odin Ugedal AuthorDate: Thu, 24 Jun 2021 13:18:15 +02:00 Committer: Peter Zijlstra CommitterDate: Mon, 28 Jun 2021 15:42:24 +02:00 sched/fair: Ensure _sum and _avg values stay consistent The _sum and _avg values are in general sync together with the PELT divider. They are however not always completely in perfect sync, resulting in situations where _sum gets to zero while _avg stays positive. Such situations are undesirable. This comes from the fact that PELT will increase period_contrib, also increasing the PELT divider, without updating _sum and _avg values to stay in perfect sync where (_sum == _avg * divider). However, such PELT change will never lower _sum, making it impossible to end up in a situation where _sum is zero and _avg is not. Therefore, we need to ensure that when subtracting load outside PELT, that when _sum is zero, _avg is also set to zero. This occurs when (_sum < _avg * divider), and the subtracted (_avg * divider) is bigger or equal to the current _sum, while the subtracted _avg is smaller than the current _avg. Reported-by: Sachin Sant Reported-by: Naresh Kamboju Signed-off-by: Odin Ugedal Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Vincent Guittot Tested-by: Sachin Sant Link: https://lore.kernel.org/r/20210624111815.57937-1-odin@uged.al --- kernel/sched/fair.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 4a3e61a..45edf61 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3657,15 +3657,15 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq) r = removed_load; sub_positive(&sa->load_avg, r); - sub_positive(&sa->load_sum, r * divider); + sa->load_sum = sa->load_avg * divider; r = removed_util; sub_positive(&sa->util_avg, r); - sub_positive(&sa->util_sum, r * divider); + sa->util_sum = sa->util_avg * divider; r = removed_runnable; sub_positive(&sa->runnable_avg, r); - sub_positive(&sa->runnable_sum, r * divider); + sa->runnable_sum = sa->runnable_avg * divider; /* * removed_runnable is the unweighted version of removed_load so we