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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE52EC433F5 for ; Wed, 29 Sep 2021 19:45:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 87C086152A for ; Wed, 29 Sep 2021 19:45:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344377AbhI2TrW (ORCPT ); Wed, 29 Sep 2021 15:47:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:35338 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244887AbhI2TrV (ORCPT ); Wed, 29 Sep 2021 15:47:21 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 754AA613DA; Wed, 29 Sep 2021 19:45:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1632944740; bh=SSBizUwzU7P1hfnNjMjgmannJ7niY7VHv9x1ZCMas4k=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=tpxxHwv9+B6xIRrrjrAA+VD6FGEUE+E/hPXl0STStgtE+sqgCeJSK14WYNeaHKS9I 9mpg92OrfybCRFoiqbm+c7AY7jKAzBfdaa7AWCTaNMNcd9YlTkt4c6+hl+X2uOPhFb ifijczsbJ4tnHu2EcwGAlFPXhdCBUmTOwHdDqV298HapBXB0W9lPw7gwx4plz9yadt VmcImQYaNfxUgtAEsQX84CO/KUT3MlbfajqTtahgWHt2p1RG5MFhPKmGHKv0+XQpW4 lTwJC4ttuTOhXJ3TXcdLriNH4CwjpHBZUFrB0uv7rTOxBJ+73Dnb5JSHIGaRSOd8GB b0imnaJ1WSSwg== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 4A3A55C1309; Wed, 29 Sep 2021 12:45:40 -0700 (PDT) Date: Wed, 29 Sep 2021 12:45:40 -0700 From: "Paul E. McKenney" To: Peter Zijlstra Cc: gor@linux.ibm.com, jpoimboe@redhat.com, jikos@kernel.org, mbenes@suse.cz, pmladek@suse.com, mingo@kernel.org, linux-kernel@vger.kernel.org, joe.lawrence@redhat.com, fweisbec@gmail.com, tglx@linutronix.de, hca@linux.ibm.com, svens@linux.ibm.com, sumanthk@linux.ibm.com, live-patching@vger.kernel.org, rostedt@goodmis.org, x86@kernel.org Subject: Re: [RFC][PATCH v2 08/11] context_tracking,rcu: Replace RCU dynticks counter with context_tracking Message-ID: <20210929194540.GZ880162@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org References: <20210929151723.162004989@infradead.org> <20210929152429.007420590@infradead.org> <20210929183701.GY880162@paulmck-ThinkPad-P17-Gen-1> <20210929191326.GZ4323@worktop.programming.kicks-ass.net> <20210929192431.GG5106@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210929192431.GG5106@worktop.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org On Wed, Sep 29, 2021 at 09:24:31PM +0200, Peter Zijlstra wrote: > On Wed, Sep 29, 2021 at 09:13:26PM +0200, Peter Zijlstra wrote: > > On Wed, Sep 29, 2021 at 11:37:01AM -0700, Paul E. McKenney wrote: > > > > > And what happens to all of this in !CONFIG_CONTEXT_TRACKING kernels? > > > Of course, RCU needs it unconditionally. (There appear to be at least > > > parts of it that are unconditionally available, but I figured that I > > > should ask. Especially given the !CONFIG_CONTEXT_TRACKING definition > > > of the __context_tracking_cpu_seq() function.) > > > > For !CONFIG_CONTEXT_TRACKING it goes *poof*. > > > > Since the thing was called dynticks, I presumed it was actually dynticks > > only, silly me (also, I didn't see any obvious !context_tracking usage > > of it, i'll go audit it more carefully. > > Oh argh, it does idle too... damn. And I don't suppose having 2 counters > is going to be nice :/ > > I'll go back to thinking about this. Glad I could help? For some definition of "help"? ;-) Thanx, Paul