From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gentwo.org (gentwo.org [62.72.0.81]) (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 5DBB92D46CB for ; Wed, 3 Sep 2025 20:43:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.72.0.81 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756932229; cv=none; b=B6cPWVMaPRgpt/ixKiFn0fEDv1wgtaDdWTvMnpRuUJQXIHCOGsRWU0wWP689jgmxSytDdFCZE9u4CR5cXHmno8aNhSBILdQvTcw0E7H4Z12FpqK4JxxmRBf2Pwqw3yzhGFeVFonhopZO52N3xfYnZGP1c/6JPe3l4WanuuWvpFs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756932229; c=relaxed/simple; bh=4iUM+il3WPoOqYkawtnO/d+wiaQWAu4xGyfE7VMDBBQ=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=MhOc32nLkKS4+BISDB0rHhC1ExJGsXT3I2U6BA4QUsSpZsZaYyQlmxAeNubTDGJJu7TP9JTGax5mXBS8gd7lBe0LYaPQEkoSBqavZcWQQQuZ900ljcwTUHn+DfWu4fruSSTXe3bNeKBM5vAc2C7Gsndl1BIp747a8H4HJAnwLJk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=gentwo.org; spf=pass smtp.mailfrom=gentwo.org; dkim=pass (1024-bit key) header.d=gentwo.org header.i=@gentwo.org header.b=kdDzlrhD; arc=none smtp.client-ip=62.72.0.81 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=gentwo.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gentwo.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=gentwo.org header.i=@gentwo.org header.b="kdDzlrhD" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gentwo.org; s=default; t=1756931596; bh=4iUM+il3WPoOqYkawtnO/d+wiaQWAu4xGyfE7VMDBBQ=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=kdDzlrhDwtc98J0QsaSJ9bF6jG31fVtMfjczNzT/xehdJ/zVoY1z7JQDM3g0W9lKy 1Nv4AdDROwVHe3W54M3dmH/UGj7QbVVfG8wp+HZIaCo43Z3K8Yay2Bu8weQog7Dlwm NB2xPpfCFkWJihu7wePGx3AvuJXcZHvg/sLxv61g= Received: by gentwo.org (Postfix, from userid 1003) id B548E4038E; Wed, 3 Sep 2025 13:33:16 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by gentwo.org (Postfix) with ESMTP id B0D56401F6; Wed, 3 Sep 2025 13:33:16 -0700 (PDT) Date: Wed, 3 Sep 2025 13:33:16 -0700 (PDT) From: "Christoph Lameter (Ampere)" To: Vincent Guittot cc: Valentin Schneider , Adam Li , mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, frederic@kernel.org, linux-kernel@vger.kernel.org, patches@amperecomputing.com Subject: Re: [PATCH] sched/nohz: Fix NOHZ imbalance by adding options for ILB CPU In-Reply-To: Message-ID: References: <20250819025720.14794-1-adamli@os.amperecomputing.com> <7438bb3a-96d6-485a-9ecc-63829db74b39@os.amperecomputing.com> <1db2d6df-16ff-4521-ada5-da585b87b06f@os.amperecomputing.com> <916176fe-ad43-9dd2-ed1c-6f05f838d491@gentwo.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Wed, 3 Sep 2025, Vincent Guittot wrote: > > AFAICT we have (at least) two options: > > 1) Trigger NOHZ balancing on a busy housekeeping CPU (what this patch does) Isnt there a third option? 3) Trigger load balancing if on a NOHZ_FULL cpu and multiple processes are running on it.