From nobody Sun Feb 8 14:56:22 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BEFF92253AB; Fri, 14 Nov 2025 12:19:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763122747; cv=none; b=knpPocJaIP0ydLXlPrBMzXcCQFCNB1O8DYMQPXP8NXofENroGxjOx5LT7ElBdUpwRZoCBY1ScXoht8cNfJJPw+B1bdvaj5sMqjnTJ94bHAZzEeiWyRdU37ZwBOhc3mLa1TPOzxp8uyBrVXXIO7Mibclb+WhTpJJGsUooWPZgyE8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763122747; c=relaxed/simple; bh=vAzIE/p4lFPvHgcsb3/HIxzYdFihVsANkGJERJtmC7M=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=fzVVWZeq9qesw743mcBeDCmTay2APF8NO83U1TGLk54ap58SL2XAQDpfzXKO09rSnfBEzzzmyKpziUi/wRzE1o6txScLYbXVcuUPHUn0HUszvqejAR0XWbEC48VTST1YVxH0f07R6UAoXuNftFXHfbvWBKoyYlMvX3wR24iwE5w= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Vtarz58/; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=vKTQVFBT; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Vtarz58/"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="vKTQVFBT" Date: Fri, 14 Nov 2025 12:19:02 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1763122744; 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=XdPdQHAym+93doUBvL8JJBkLYrlUoRzNay54DLhR4+I=; b=Vtarz58/Q3eIawiEbedIRuV7X/qmjPvzHkT7cSO36uvX0L+8L2YSbb+/BOW1u2tonnWlfs cyLT54dUJzjmhNVhwqA/Wnbcfm6UnLvIA4oXOzfXFLajQy4kXQ/pIE9wfHlOR8oMsEjN8h bBN+fhyN64KLH93fo/IQO58O/5LMa0rD+fWpyea2PqoLi6NCjguVl3nfLm/ylEk0TJ4BTT dXBsLG3lgZtJ922QD2otGb8J/pyu0q93F5ORldsxyak19qm33KKMq6llDXbx31tswhdNKu 8ooBHhfRmB0vXwigAszXLojiQPjsTHvrYiu3tSWc2R4VOB/cIJXsZM60PE0m5A== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1763122744; 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=XdPdQHAym+93doUBvL8JJBkLYrlUoRzNay54DLhR4+I=; b=vKTQVFBTMbO+QXfB29tzSkqToeOMH1mMS+cuudNcUpYRcWPbaYK+5nG5GI4QcJv3oKDX0l D5xhBsZHZuUD3/Ag== From: "tip-bot2 for Peter Zijlstra" 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: Revert max_newidle_lb_cost bump Cc: Joseph Salisbury , Adam Li , Dietmar Eggemann , Hazem Mohamed Abuelfotoh , "Peter Zijlstra (Intel)" , Chris Mason , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20251107161739.406147760@infradead.org> References: <20251107161739.406147760@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <176312274291.498.4509981768126901496.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the sched/core branch of tip: Commit-ID: 63bdc220840d16b370fdf678b7d916552fef046e Gitweb: https://git.kernel.org/tip/63bdc220840d16b370fdf678b7d916552= fef046e Author: Peter Zijlstra AuthorDate: Fri, 07 Nov 2025 17:01:20 +01:00 Committer: Peter Zijlstra CommitterDate: Fri, 14 Nov 2025 13:03:07 +01:00 sched/fair: Revert max_newidle_lb_cost bump Many people reported regressions on their database workloads due to: 155213a2aed4 ("sched/fair: Bump sd->max_newidle_lb_cost when newidle bala= nce fails") For instance Adam Li reported a 6% regression on SpecJBB. Conversely this will regress schbench again; on my machine from 2.22 Mrps/s down to 2.04 Mrps/s. Reported-by: Joseph Salisbury Reported-by: Adam Li Reported-by: Dietmar Eggemann Reported-by: Hazem Mohamed Abuelfotoh Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Dietmar Eggemann Tested-by: Dietmar Eggemann Tested-by: Chris Mason Link: https://lkml.kernel.org/r/20250626144017.1510594-2-clm@fb.com Link: https://lkml.kernel.org/r/006c9df2-b691-47f1-82e6-e233c3f91faf@oracle= .com Link: https://patch.msgid.link/20251107161739.406147760@infradead.org --- kernel/sched/fair.c | 19 +++---------------- 1 file changed, 3 insertions(+), 16 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 11d480e..bfb8935 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -12229,14 +12229,8 @@ static inline bool update_newidle_cost(struct sche= d_domain *sd, u64 cost) /* * Track max cost of a domain to make sure to not delay the * next wakeup on the CPU. - * - * sched_balance_newidle() bumps the cost whenever newidle - * balance fails, and we don't want things to grow out of - * control. Use the sysctl_sched_migration_cost as the upper - * limit, plus a litle extra to avoid off by ones. */ - sd->max_newidle_lb_cost =3D - min(cost, sysctl_sched_migration_cost + 200); + sd->max_newidle_lb_cost =3D cost; sd->last_decay_max_lb_cost =3D jiffies; } else if (time_after(jiffies, sd->last_decay_max_lb_cost + HZ)) { /* @@ -12919,17 +12913,10 @@ static int sched_balance_newidle(struct rq *this_= rq, struct rq_flags *rf) =20 t1 =3D sched_clock_cpu(this_cpu); domain_cost =3D t1 - t0; + update_newidle_cost(sd, domain_cost); + curr_cost +=3D domain_cost; t0 =3D t1; - - /* - * Failing newidle means it is not effective; - * bump the cost so we end up doing less of it. - */ - if (!pulled_task) - domain_cost =3D (3 * sd->max_newidle_lb_cost) / 2; - - update_newidle_cost(sd, domain_cost); } =20 /*