From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 511B0202C2D for ; Tue, 4 Mar 2025 13:24:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741094662; cv=none; b=DVrFGE7FmaBsKATILD7Iu/q3zzjyc5CN3GNpY/FcvB4mJVevADlYgAKSIhdMQ/mLidGyRddItAQZOUC5S/CBdLJ2loem3+G36XrUaBgShXgdgYg5+ZJjzfPoz7wI0Mhmzc+Hrbb+mX8J3P4LeBbSXTsTgRVo111a9tOnULYTPPo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741094662; c=relaxed/simple; bh=VWJ2JqFcp8Axpz+IPJNcbUoYnVh59FXLktDoI76xwVg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TmS993RDJemG9Uk1IBYuvRz510hjvcy8d9LznCVVrV6nm7alfYSYcJ9Vm0zMSR4/Vyv5zetl8RS8hKMOf+w4mue6vmQfSLsamhR2t0OqXN6JtxPnYcK9irQ/Tti4lNuxxB/GVSz4BL5QTYgM7yc8dMz8sWtYp5rLMMgTSaHkKnI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VMLERQIx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VMLERQIx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D4560C4CEE7; Tue, 4 Mar 2025 13:24:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741094662; bh=VWJ2JqFcp8Axpz+IPJNcbUoYnVh59FXLktDoI76xwVg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VMLERQIxNMhU3OGu18p2IGnv/CM3zZB5bg7fqAAoNLupRSEvU3zIyVsZ79Fte9l0b zE3WLkMlNNvblhS260rFQ+uDkjmFgCDgFoSlocSDLVy3xTmUrYtIbG4kKY4dy3gZEI HV4EYw4xLMW2bQJLKdG6lCmtXhvUbSgR4NTZU9AAf3AowOXsj3wGOG+Lip4tJA50ox 4B3KvfyXKr1CI2yyrgW1mgCikY4oz2RQ/5Ukhjl+f6sxiHuGLxlrsuEOSqsyug8YfY KPMKKvlr6G0rkdwyXtOFYhg9Ftg2FS9/E3kW0SkzaC9ZoWbB1OmaOXK5p3QpTmc5SG Mkwk5c5yTBqZA== Date: Tue, 4 Mar 2025 14:24:19 +0100 From: Frederic Weisbecker To: Phil Auld Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Juri Lelli , Waiman Long , Vishal Chourasia , Vineeth Reddy Subject: Re: [PATCH v2] sched/isolation: Make use of more than one housekeeping cpu Message-ID: References: <20250218184618.1331715-1-pauld@redhat.com> 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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250218184618.1331715-1-pauld@redhat.com> Le Tue, Feb 18, 2025 at 06:46:18PM +0000, Phil Auld a écrit : > The exising code uses housekeeping_any_cpu() to select a cpu for > a given housekeeping task. However, this often ends up calling > cpumask_any_and() which is defined as cpumask_first_and() which has > the effect of alyways using the first cpu among those available. > > The same applies when multiple NUMA nodes are involved. In that > case the first cpu in the local node is chosen which does provide > a bit of spreading but with multiple HK cpus per node the same > issues arise. > > We have numerous cases where a single HK cpu just cannot keep up > and the remote_tick warning fires. It also can lead to the other > things (orchastration sw, HA keepalives etc) on the HK cpus getting > starved which leads to other issues. In these cases we recommend > increasing the number of HK cpus. But... that only helps the > userspace tasks somewhat. It does not help the actual housekeeping > part. > > Spread the HK work out by having housekeeping_any_cpu() and > sched_numa_find_closest() use cpumask_any_and_distribute() > instead of cpumask_any_and(). > > Signed-off-by: Phil Auld > Reviewed-by: Waiman Long > Cc: Peter Zijlstra > Cc: Juri Lelli > Cc: Frederic Weisbecker > Cc: Waiman Long > Cc: linux-kernel@vger.kernel.org > Link: https://lore.kernel.org/lkml/20250211141437.GA349314@pauld.westford.csb/ Acked-by: Frederic Weisbecker