From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752491AbaFCK1N (ORCPT ); Tue, 3 Jun 2014 06:27:13 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:60514 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752252AbaFCK1K (ORCPT ); Tue, 3 Jun 2014 06:27:10 -0400 Date: Tue, 3 Jun 2014 11:26:46 +0100 From: Will Deacon To: Kevin Hilman Cc: Catalin Marinas , "larry.bassel@linaro.org \"linux-kernel@vger.kernel.org\"" , "linux-arm-kernel@lists.infradead.org" , "linaro-kernel@lists.linaro.org" Subject: Re: [PATCH v6 2/2] arm64: enable context tracking Message-ID: <20140603102646.GB23149@arm.com> References: <1401399904-24471-1-git-send-email-larry.bassel@linaro.org> <1401399904-24471-3-git-send-email-larry.bassel@linaro.org> <20140530182349.GI22895@arm.com> <7hioonythl.fsf@paris.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7hioonythl.fsf@paris.lan> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi guys, On Fri, May 30, 2014 at 08:08:38PM +0100, Kevin Hilman wrote: > Will Deacon writes: > > I'd like to give these some stress testing before it gets merged, so I'm > > not sure if it'll make it for 3.16 given where we are at the moment. > > FWIW, this feature is disabled by default. I use the following kconfig > fragment to enable the various parts I use for testing: > > CONFIG_NO_HZ=y > CONFIG_NO_HZ_FULL=y > CONFIG_NO_HZ_FULL_ALL=y > CONFIG_NO_HZ_FULL_SYSIDLE=y > > # default to power-efficient workqueues (which are then set to unbound) > CONFIG_WQ_POWER_EFFICIENT_DEFAULT=y > > # lockup detector sets a 4s timer on every CPU, which wakes CPUs > # from idle. (alternately, can be controlled via procfs, > # e.g: echo 0 > /proc/sys/kernel/watchdog) > #CONFIG_LOCKUP_DETECTOR=n I had a go with this, but I couldn't seem to trigger any context tracking without forcing CONFIG_CONTEXT_TRACKING_FORCE=y. Does that mean we're missing something else? Anyway, with that forced on, I see the following during boot: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at kernel/rcu/tree.c:418 rcu_eqs_enter+0x84/0xa4() Modules linked in: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.15.0-rc8+ #5 Call trace: [] dump_backtrace+0x0/0x130 [] show_stack+0x10/0x1c [] dump_stack+0x74/0xbc [] warn_slowpath_common+0x8c/0xb4 [] warn_slowpath_null+0x14/0x20 [] rcu_eqs_enter+0x80/0xa4 [] rcu_idle_enter+0x20/0x50 [] cpu_startup_entry+0x118/0x184 [] rest_init+0x7c/0x88 [] start_kernel+0x368/0x37c ---[ end trace c17313e162496e65 ]--- ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at kernel/rcu/tree.c:541 rcu_eqs_exit+0xb0/0xbc() Modules linked in: CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W 3.15.0-rc8+ #5 Call trace: [] dump_backtrace+0x0/0x130 [] show_stack+0x10/0x1c [] dump_stack+0x74/0xbc [] warn_slowpath_common+0x8c/0xb4 [] warn_slowpath_null+0x14/0x20 [] rcu_eqs_exit+0xac/0xbc [] rcu_user_exit+0xc/0x18 [] context_tracking_user_exit+0xc4/0xd4 [] el1_irq+0x58/0xd4 [] cpu_startup_entry+0x11c/0x184 [] rest_init+0x7c/0x88 [] start_kernel+0x368/0x37c ---[ end trace c17313e162496e66 ]--- Can you take a look please? I had to fix up some conflicts to apply your patches against our for-next branch, so I've put a branch here for you to look at: git://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git aarch64/context-tracking Cheers, Will