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 330A9C433F5 for ; Tue, 3 May 2022 13:33:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236251AbiECNhH (ORCPT ); Tue, 3 May 2022 09:37:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234955AbiECNhD (ORCPT ); Tue, 3 May 2022 09:37:03 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 35257338BD for ; Tue, 3 May 2022 06:33:31 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E221C1042; Tue, 3 May 2022 06:33:30 -0700 (PDT) Received: from lakrids (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DFC813F774; Tue, 3 May 2022 06:33:28 -0700 (PDT) Date: Tue, 3 May 2022 14:33:22 +0100 From: Mark Rutland To: Frederic Weisbecker Cc: LKML , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: Re: [PATCH 10/21] context_tracking: Take idle eqs entrypoints over RCU Message-ID: References: <20220503100051.2799723-1-frederic@kernel.org> <20220503100051.2799723-11-frederic@kernel.org> <20220503114225.GA2799075@lothringen> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220503114225.GA2799075@lothringen> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 03, 2022 at 01:42:25PM +0200, Frederic Weisbecker wrote: > On Tue, May 03, 2022 at 12:02:51PM +0100, Mark Rutland wrote: > > Hi Frederic, > > > > On Tue, May 03, 2022 at 12:00:40PM +0200, Frederic Weisbecker wrote: > > > The RCU dynticks counter is going to be merged into the context tracking > > > subsystem. Start with moving the idle extended quiescent states > > > entrypoints to context tracking. For now those are dumb redirections to > > > existing RCU calls. > > > > I was a bit confused looking at this, because that redirection only exists for > > CONFIG_CONTEXT_TRACKING, and is empty otherwise. > > > > I see this patch makes TREE_RCU select CONTEXT_TRACKING, which means that > > works. Since that also means building the rest of the context tracking code, I > > think it'd be worth mentioning that in the commit message. > > Not exactly, it only builds a minimal version of CONTEXT_TRACKING, which maps > to roughly the vanilla RCU-idle code. > > The user tracking part (which is the vanilla CONTEXT_TRACKING) now becomes > CONFIG_CONTEXT_TRACKING_USER Ah, sorry. That makes sense to me now! > > Do all architectures which can use TREE_RCU today already support context > > tracking? If not, do those work by default? > > No need to, the old context tracking becomes CONFIG_CONTEXT_TRACKING_USER > which is not needed by TREE_RCU. > > Ok you're right, this is all very confusing :o) > > Let's clarify this, I'm going to do the following on the next version: > > * The current CONFIG_CONTEXT_TRACKING becomes CONFIG_CONTEXT_TRACKING_USER. > This part needs support from the architecture. > > * The RCU-idle functions that have been moved to context tracking will become > CONFIG_CONTEXT_TRACKING_IDLE. This part doesn't need support from the > architecture and will be set by TREE_RCU. > > Would that look clearer? I think so, yes! It would also help if the prior commit message could be explicit about the end result: After the Kconfig rework both CONFIG_CONTEXT_TRACKING_USER and CONFIG_CONTEXT_TRACKING exist, but CONFIG_CONTEXT_TRACKING will only used to decide whether to build object files with common context tracking logic. Thanks, Mark.