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 X-Spam-Level: X-Spam-Status: No, score=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8B4BC433E0 for ; Fri, 19 Feb 2021 19:46:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AAE8464EAF for ; Fri, 19 Feb 2021 19:46:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229947AbhBSTqX (ORCPT ); Fri, 19 Feb 2021 14:46:23 -0500 Received: from mail.kernel.org ([198.145.29.99]:59990 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229689AbhBSTqU (ORCPT ); Fri, 19 Feb 2021 14:46:20 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id A4EF264D99; Fri, 19 Feb 2021 19:45:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1613763939; bh=rRTp7Rx//A9OI8uHGPI+kbixSlhwW7/UBwaQxooAwcY=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=MCn45UTB60iS+AK5M2DxA21L78Zqoha72S4i5mtZjEAPZHTwpFcRFpCSrwIrE+Ezi WUtmYKbiG6j+ybm8PTVcnsHBQhpgIdw+r3l6XhHWIAW8HEpVltH7IB7g702s1lukcZ NnKZk7Fpbi4gv2tnfYkqxv0RvqeB9I3vHxlDpsaoTVWBKEFRBSTN4IueCABuSTzmS9 H+K3AISB5UxHB/rmdiVYP0T35cMBNbcwexv1x7AnhESXgr81LZDAi+3XmwpGQteKoE JZtulcpGwhmyEkCw/zaTakshdPAtGxPIV1LHRkAcKv+jUB6LPYYpONh0o5VVT3ZO96 oZv29ioelHIhg== Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 5733C3520E6A; Fri, 19 Feb 2021 11:45:39 -0800 (PST) Date: Fri, 19 Feb 2021 11:45:39 -0800 From: "Paul E. McKenney" To: Steven Rostedt Cc: Uladzislau Rezki , Sebastian Andrzej Siewior , Masami Hiramatsu , Ingo Molnar , Peter Zijlstra , Thomas Gleixner , LKML , RCU , Michael Ellerman , Andrew Morton , Daniel Axtens , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Michal Hocko , "Theodore Y . Ts'o" , Oleksiy Avramchenko Subject: Re: [PATCH] kprobes: Fix to delay the kprobes jump optimization Message-ID: <20210219194539.GZ2743@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20210218151554.GQ2743@paulmck-ThinkPad-P72> <20210219081755.eucq4srbam6wg2gm@linutronix.de> <20210219104958.GA34308@pc638.lan> <20210219105710.d626zexj6vzt6k6y@linutronix.de> <20210219111301.GA34441@pc638.lan> <20210219111738.go6i2fdzvavpotxd@linutronix.de> <20210219112357.GA34462@pc638.lan> <20210219112751.GA34528@pc638.lan> <20210219181811.GY2743@paulmck-ThinkPad-P72> <20210219141429.53def012@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210219141429.53def012@gandalf.local.home> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 19, 2021 at 02:14:29PM -0500, Steven Rostedt wrote: > On Fri, 19 Feb 2021 10:18:11 -0800 > "Paul E. McKenney" wrote: > > > We can further prevent entry into dyntick-idle state until > > the ksoftirqd kthreads have been spawned, which means that if softirq > > handlers must be deferred, they will be resumed within one jiffy by the > > next scheduler-clock interrupt. > > Why not just prevent entry into dyntick-idle state until the system is > finished booting? As you said; There should be no latency-sensitive > applications running, until after we started the system. Exactly, and that is the effect of patch to rcu_needs_cpu() that I just now posted. Ah, your point is that if the tick keeps running, there is no need to modify softirq? Good point, and I will test that, thank you!!! Thanx, Paul