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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 7AA61C43141 for ; Wed, 20 Jun 2018 16:12:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1CA9D20875 for ; Wed, 20 Jun 2018 16:12:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1CA9D20875 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754344AbeFTQMA (ORCPT ); Wed, 20 Jun 2018 12:12:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:39036 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754113AbeFTQL7 (ORCPT ); Wed, 20 Jun 2018 12:11:59 -0400 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 05FC020836; Wed, 20 Jun 2018 16:11:57 +0000 (UTC) Date: Wed, 20 Jun 2018 12:11:56 -0400 From: Steven Rostedt To: "Paul E. McKenney" Cc: Byungchul Park , jiangshanlai@gmail.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org, kernel-team@lge.com, joel@joelfernandes.org Subject: Re: [RFC 1/2] rcu: Do prepare and cleanup idle depending on in_nmi() Message-ID: <20180620121156.4da98db2@gandalf.local.home> In-Reply-To: <20180620155658.GU3593@linux.vnet.ibm.com> References: <1529484440-20634-1-git-send-email-byungchul.park@lge.com> <20180620145058.GP3593@linux.vnet.ibm.com> <20180620114335.7a314642@gandalf.local.home> <20180620155658.GU3593@linux.vnet.ibm.com> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 20 Jun 2018 08:56:58 -0700 "Paul E. McKenney" wrote: > OK, so in theory this change is safe from a tracing perspective. But > it does add conditionals to a fastpath. Does it? I see it replacing two conditions from both rcu_irq_enter/exit() with a single one in rcu_nmi_enter/exit(). Sure it adds one to rcu_nmi_enter() but that's a far less fast path than rcu_irq_enter(), which this patch removes a conditional from. -- Steve