From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5082C34388B for ; Tue, 9 Jun 2026 15:34:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781019263; cv=none; b=MoajZwdAotpgIrCvjVpqjnk3jRIKiGd9wvLWR4ntqq+a18pv33S5TKZbJQFbF8rj282rxvpouw5DPnkpA/b/Qudv2pj3xIdJfy97Ol7W7vWyVR8aX2Dgbo+sKjqhJZOKAx1s/RbGtNwoh2ZbfGlH50Ad7gjkfi/r3vTu7rwpihE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781019263; c=relaxed/simple; bh=Ah+3oqtBUAPq3UWkbHx1REspasMLPgjO/UNALPiWFZA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=VelZBRIzg+fgIT/QSfpejlOO98Q9pMBXz0HBchz4/3yjpFjaLR8ORjcr/Go0SjbMhCWNjWOHrG7v9/1d7jOCju/QdB1q59tuQOHXg7QT4GrxPJAT7cLIknkMk/Zvia2n5Zvr5SiRF6hjIF+w7PJDk7388Fi79gulUI/4zi704Ps= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=Qeep2YtR; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="Qeep2YtR" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A7A433528; Tue, 9 Jun 2026 08:34:15 -0700 (PDT) Received: from [10.57.30.26] (unknown [10.57.30.26]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5F0293FB90; Tue, 9 Jun 2026 08:34:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1781019260; bh=Ah+3oqtBUAPq3UWkbHx1REspasMLPgjO/UNALPiWFZA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Qeep2YtR6SCspVbumhk+imB5sD7Mo0g2CqM9NkrFpRVfaKT8Bb6XiTRtj97V+g3rm pHGG9G/Q1QlLdxtuscAWhD3TYCeKWi0tmO9cPOHbx/EuJ4sxKNqCCWobtU5vztLapa RaifXDgFqS7MphkXkgIuLfSX8Q4f8fHUA3uSRS4Q= Message-ID: Date: Tue, 9 Jun 2026 16:34:17 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] timers/migration: Temporarily disable per capacity hierarchies To: Frederic Weisbecker , Thomas Gleixner Cc: LKML , Sehee Jeong , Anna-Maria Behnsen References: <20260609123356.28449-1-frederic@kernel.org> Content-Language: en-US From: Christian Loehle In-Reply-To: <20260609123356.28449-1-frederic@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/9/26 13:33, Frederic Weisbecker wrote: > Some workloads with different CPU capacities consume more power with > timer migration than before. The recently introduced per capacity > hierarchies were supposed to alleviate this problem. However it appears > to also regress other types of workloads, especially when plenty of > capacities live together in the same machine. > > Disable the feature until a reasonable solution is found. > > Fixes: 098cbaad8e57 ("timers/migration: Split per-capacity hierarchies") > Reported-by: Christian Loehle > Signed-off-by: Frederic Weisbecker > --- > kernel/time/timer_migration.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/time/timer_migration.c b/kernel/time/timer_migration.c > index 548d84955f4c..e9d96d96e251 100644 > --- a/kernel/time/timer_migration.c > +++ b/kernel/time/timer_migration.c > @@ -1473,7 +1473,7 @@ static unsigned int tmigr_get_capacity(int cpu) > * timekeeper must then belong to the same hierarchy as all the nohz_full > * CPUs. Simply turn off capacity awareness when nohz_full is running. > */ > - if (tick_nohz_full_enabled()) > + if (tick_nohz_full_enabled() || !IS_ENABLED(CONFIG_BROKEN)) > return SCHED_CAPACITY_SCALE; > else > return arch_scale_cpu_capacity(cpu); FWIW Reviewed-by: Christian Loehle Thanks for looking into this after the late response! I have something based on avg_idle which doesn't look unreasonable on first glance, I'll do some more testing and hopefully post it with some number soon!