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=-14.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,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 C1027C4727F for ; Tue, 29 Sep 2020 07:57:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8BB412075F for ; Tue, 29 Sep 2020 07:57:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="M+sBsSBn"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="haxjIhCR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727711AbgI2H5B (ORCPT ); Tue, 29 Sep 2020 03:57:01 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:44402 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727522AbgI2H4w (ORCPT ); Tue, 29 Sep 2020 03:56:52 -0400 Date: Tue, 29 Sep 2020 07:56:48 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1601366209; 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=f1XYo2+cH1VCpRIz0lVKMzV6nqe5Kwfr/eW0vnIq1OU=; b=M+sBsSBnUxW8wpCM1vVMZ2kGfLYui19LgLQglgBYRPsKwZpnSpHX0/QefmiJxIIX+9O1z4 cnXmYWRbLa7kHjQ5byaOygpG7VMSU6YjEbSRq+mltet3cgfVnNhxsefHKnwD+I1UbCQB0I xxf0R1FTdrNUiXq9L6cNUSqcDuOLhSDozO+KyUQQI1Za+EGd7SErZyhcIYmxCtVfbfVLpY FY81VkczbvhQhhTmKhm4qiK/zsyjt1vfOhAcsfjJPxMI0Tbd1BOpg1qfalgpkTSgtjH/DI nmkRD4jGOFGX8Bcg+iG3JloaTG659pmPat9AVyetTgtOP77XjRghBAlu/FjENQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1601366209; 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=f1XYo2+cH1VCpRIz0lVKMzV6nqe5Kwfr/eW0vnIq1OU=; b=haxjIhCRRjpCTLbwy+NKtBO19zBgUb1b334HwcKxx50mkD7myRWZs/WfRxzVqj2LYzSoGr sE+90nAuZsKGA2Dw== From: "tip-bot2 for Vincent Guittot" 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: Minimize concurrent LBs between domain level Cc: Vincent Guittot , "Peter Zijlstra (Intel)" , Phil Auld , x86 , LKML In-Reply-To: <20200921072424.14813-4-vincent.guittot@linaro.org> References: <20200921072424.14813-4-vincent.guittot@linaro.org> MIME-Version: 1.0 Message-ID: <160136620899.7002.5463550699330938953.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: e4d32e4d5444977d8dc25fa98b3ce0a65544db8c Gitweb: https://git.kernel.org/tip/e4d32e4d5444977d8dc25fa98b3ce0a65544db8c Author: Vincent Guittot AuthorDate: Mon, 21 Sep 2020 09:24:23 +02:00 Committer: Peter Zijlstra CommitterDate: Fri, 25 Sep 2020 14:23:26 +02:00 sched/fair: Minimize concurrent LBs between domain level sched domains tend to trigger simultaneously the load balance loop but the larger domains often need more time to collect statistics. This slowness makes the larger domain trying to detach tasks from a rq whereas tasks already migrated somewhere else at a sub-domain level. This is not a real problem for idle LB because the period of smaller domains will increase with its CPUs being busy and this will let time for higher ones to pulled tasks. But this becomes a problem when all CPUs are already busy because all domains stay synced when they trigger their LB. A simple way to minimize simultaneous LB of all domains is to decrement the the busy interval by 1 jiffies. Because of the busy_factor, the interval of larger domain will not be a multiple of smaller ones anymore. Signed-off-by: Vincent Guittot Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Phil Auld Link: https://lkml.kernel.org/r/20200921072424.14813-4-vincent.guittot@linaro.org --- kernel/sched/fair.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 5e3add3..24a5ee6 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9790,6 +9790,15 @@ get_sd_balance_interval(struct sched_domain *sd, int cpu_busy) /* scale ms to jiffies */ interval = msecs_to_jiffies(interval); + + /* + * Reduce likelihood of busy balancing at higher domains racing with + * balancing at lower domains by preventing their balancing periods + * from being multiples of each other. + */ + if (cpu_busy) + interval -= 1; + interval = clamp(interval, 1UL, max_load_balance_interval); return interval;