From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38B9EC433EF for ; Tue, 10 May 2022 17:15:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347838AbiEJRS6 (ORCPT ); Tue, 10 May 2022 13:18:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51664 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237570AbiEJRS4 (ORCPT ); Tue, 10 May 2022 13:18:56 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 709E22BF30A; Tue, 10 May 2022 10:14:58 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 015986188C; Tue, 10 May 2022 17:14:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5892DC385C2; Tue, 10 May 2022 17:14:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1652202897; bh=5y/vAVwde0HqnA5nQ1KPT5/RVLZLMkTULnrLQbWw3H8=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=LqcoBJ7jxEphDO07qYlcF5eiAkCtgKjTr8+CUbt9u7l15bQdiDnJ2CaUyafm/JI3r rGErienokqkFDULf7MjxZiTvEHDf1qNADw+/gxtlwkfyU/Q0EzEcV6UwbpBgCLK4Hf Kt/pC8LQa/Y+yYMbgl2O+d/lRZCrFEOxonwq/+qb/boHViC371H+v/swLHeJ+fPss9 6hGgKuqAAzz8NS0SQW+8wuDTtAc4jnfw7aRDjEKkFt6CK8ULXmyzpPymeqQrCesX22 rrFnwSGp8tzix7WU5Ggord8X81BsXHkuIG+N0LguyssLMAvhE3oHGGFZl1awD5RUua x9hgKSvwq+YnA== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id E76D55C0602; Tue, 10 May 2022 10:14:56 -0700 (PDT) Date: Tue, 10 May 2022 10:14:56 -0700 From: "Paul E. McKenney" To: Sebastian Andrzej Siewior Cc: "Uladzislau Rezki (Sony)" , LKML , RCU , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Oleksiy Avramchenko Subject: Re: [PATCH] rcu/nocb: Add an option to ON/OFF an offloading from RT context Message-ID: <20220510171456.GV1790663@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org References: <20220505101641.28472-1-urezki@gmail.com> <20220505190915.GW1790663@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 10, 2022 at 04:07:23PM +0200, Sebastian Andrzej Siewior wrote: > On 2022-05-05 12:09:15 [-0700], Paul E. McKenney wrote: > > All good points! > > > > Some questions and comments below. > > > > Adding Sebastian on CC for his perspective. > > Thank you. > I may missing things, I tried to digest the thread… > > In my understanding: The boosting option is used to allow a SCHED_OTHER > task within a RCU section to allow to leave the RCU section while tasks > with higher priority occupy the CPU. > As far as the RCU callbacks are concerned, I'm not aware that it would > be beneficial to run them with an elevated priority. On SMP systems, > there is the suggestion to have a housekeeping CPU and to offload the > RCU callbacks to this CPU and no to bother the CPU with the RT workload. Agreed, even within RT, there are multiple ways to get this job done. Thanx, Paul