Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755094AbcCVRaO (ORCPT ); Tue, 22 Mar 2016 13:30:14 -0400 Received: from casper.infradead.org ([85.118.1.10]:59454 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752547AbcCVRaK (ORCPT ); Tue, 22 Mar 2016 13:30:10 -0400 Date: Tue, 22 Mar 2016 18:30:05 +0100 From: Peter Zijlstra To: Chris Metcalf Cc: "Rafael J. Wysocki" , Russell King , Thomas Gleixner , Aaron Tomlin , Ingo Molnar , Andrew Morton , Daniel Thompson , x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH v3 4/4] nmi_backtrace: generate one-line reports for idle cpus Message-ID: <20160322173005.GT6344@twins.programming.kicks-ass.net> References: <1458667179-19630-1-git-send-email-cmetcalf@mellanox.com> <1458667179-19630-5-git-send-email-cmetcalf@mellanox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1458667179-19630-5-git-send-email-cmetcalf@mellanox.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1523 Lines: 42 On Tue, Mar 22, 2016 at 01:19:39PM -0400, Chris Metcalf wrote: > When doing an nmi backtrace of many cores, most of which are idle, > the output is a little overwhelming and very uninformative. Suppress > messages for cpus that are idling when they are interrupted and just > emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN". > > We do this by grouping all the cpuidle code together into a new > .cpuidle.text section, and then checking the address of the > interrupted PC to see if it lies within that section. > > This commit suitably tags x86, arm64, and tile idle routines, > and only adds in the minimal framework for other architectures. > > Acked-by: Peter Zijlstra (Intel) > Tested-by: Peter Zijlstra (Intel) > Signed-off-by: Chris Metcalf For some reason I found a few CPUs using poll_idle(). Rafael, when and why would that ever get selected as a useful idle state? When the predicted idle time is so short even C1 isn't worth it? --- a/drivers/cpuidle/driver.c +++ b/drivers/cpuidle/driver.c @@ -14,6 +14,7 @@ #include #include #include +#include #include "cpuidle.h" @@ -178,7 +179,7 @@ static void __cpuidle_driver_init(struct } #ifdef CONFIG_ARCH_HAS_CPU_RELAX -static int poll_idle(struct cpuidle_device *dev, +__cpuidle static int poll_idle(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { local_irq_enable();