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 82290C433F5 for ; Wed, 29 Sep 2021 19:27:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 66C8461505 for ; Wed, 29 Sep 2021 19:27:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346487AbhI2T2u (ORCPT ); Wed, 29 Sep 2021 15:28:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56476 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346463AbhI2T2s (ORCPT ); Wed, 29 Sep 2021 15:28:48 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F696C061765; Wed, 29 Sep 2021 12:27:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=WLQ1UteiuDxr5zMvOLEeFqf+m7DpN8OCufh9KBGNF3k=; b=lkXSqcXkuHl1H/ITAFrfgQe1P8 axZYThYtS+M8ROnfB/Nham1m61DeilgiEyW0VRh/9/h+bify1RjSZmIYYhZuOiqHeCPRSF8QiYtqC ABtb7GXWx1Gq7wilJuEwvkuml4wpD6XlalwaPTCdr82OehK7VReeLI9zwxcjprgH73HfWUU/WO9HL D37GTgtHrbODZgH2+YX74FJhvvUCV5Va9i3a2tzZ9r8w2kIW9hUDHTS402U9eABPbyCm7Xw2U9XE0 5Hxkk2Te5j52vz6eos4q3IaHDfWaiDnyIaW/lTaA2J8FlDf9jcpLldEFHVWKYc4mNAiw+65Eui2sU RG3aV7kw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mVfBw-00CA3k-2n; Wed, 29 Sep 2021 19:24:38 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id A298C981431; Wed, 29 Sep 2021 21:24:31 +0200 (CEST) Date: Wed, 29 Sep 2021 21:24:31 +0200 From: Peter Zijlstra To: "Paul E. McKenney" 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: <20210929192431.GG5106@worktop.programming.kicks-ass.net> References: <20210929151723.162004989@infradead.org> <20210929152429.007420590@infradead.org> <20210929183701.GY880162@paulmck-ThinkPad-P17-Gen-1> <20210929191326.GZ4323@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210929191326.GZ4323@worktop.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org 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.