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 59BB31E1A08 for ; Fri, 13 Dec 2024 14:34:44 +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=1734100484; cv=none; b=RpEs2jdN00SenTSrZ+XtczJ6kozHPqcRASl+jw57QkIvSCD/87NSFbdsjpYRiCAD1AGPXnxkQ85eL7XKg0QJsq9eiHrbfVNhNOYw7c+Wel2pvHH4+4rseBXl8ZI2eFsu9iYufEYlfWnSxIq/8qGtj/oyNvIzEEwEQUIJTIpHu58= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734100484; c=relaxed/simple; bh=WmozSn24zm/qMbPlMDouk38wksQoEG3qEiOEDvjbk3w=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=CLQEcYNx6CwBbYK016MuvwaISaqId7QRRdEY4fhC0jqyjLNRfypNVaSZpTzcfseOiJjvKaHT8VgSy/0RCC2MvoQ+5IPbpWqgEftdloF1+LGJYVvX5N01qUpeYkC+E87lYms3JiLBbzZcodZOOjfyBR2puu6Xt3MMnKN/N+S4ano= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oZ1hhwwf; 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="oZ1hhwwf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 973C0C4CED6; Fri, 13 Dec 2024 14:34:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1734100483; bh=WmozSn24zm/qMbPlMDouk38wksQoEG3qEiOEDvjbk3w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=oZ1hhwwfsyrP7+f8z6dU5nfKq0B5HaDlxmkTLe+jHmrypG4eZt2UJU83IUaSqk4kz cU1+/5JqGkCG+0SQMyRvB+uzu0n4wQyVn2DkOVIywNgv3hs+np8BloWQIBP9iZ1Bfx chUhpQSHh17Oz3XY6mkZ4w6q7yku7qI+EMfpVsT6NGaevsHd1NF8Ro8ocKZueAn8ed h1h+J8GodqZr1wdJZYlOJOQrXSB2S6T/59B4/IYxj/ULR4tLLN9SZGLokgykQd8axZ JIMIxwzUwNxHfoSAKmTel3MvxC3h1XkOJqu9mXmeZw6iPh0tdfevtLM77ARr79qzxg v+4lOnbC6NBWg== Date: Fri, 13 Dec 2024 15:34:41 +0100 From: Frederic Weisbecker To: Ankur Arora Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, tglx@linutronix.de, paulmck@kernel.org, mingo@kernel.org, bigeasy@linutronix.de, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, efault@gmx.de, sshegde@linux.ibm.com, boris.ostrovsky@oracle.com, Daniel Bristot de Oliveira Subject: Re: [PATCH v3 6/7] osnoise: provide quiescent states Message-ID: References: <20241213040658.2282640-1-ankur.a.arora@oracle.com> <20241213040658.2282640-7-ankur.a.arora@oracle.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: <20241213040658.2282640-7-ankur.a.arora@oracle.com> Le Thu, Dec 12, 2024 at 08:06:57PM -0800, Ankur Arora a écrit : > To reduce RCU noise for nohz_full configurations, osnoise depends > on cond_resched() providing quiescent states for PREEMPT_RCU=n > configurations. For PREEMPT_RCU=y configurations -- where > cond_resched() is a stub -- we do this by directly calling > rcu_momentary_eqs(). > > With (PREEMPT_LAZY=y, PREEMPT_DYNAMIC=n), however, we have a > configuration with (PREEMPTION=y, PREEMPT_RCU=n) where neither > of the above can help. > > Handle that by providing an explicit quiescent state here for all > configurations. > > As mentioned above this is not needed for non-stubbed cond_resched(), > but, providing a quiescent state here just pulls in one that a future > cond_resched() would provide, so doesn't cause any extra work for > this configuration. > > Cc: Paul E. McKenney > Cc: Daniel Bristot de Oliveira > Cc: Steven Rostedt > Suggested-by: Paul E. McKenney > Acked-by: Daniel Bristot de Oliveira > Signed-off-by: Ankur Arora Reviewed-by: Frederic Weisbecker