From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755112AbbGFQ1j (ORCPT ); Mon, 6 Jul 2015 12:27:39 -0400 Received: from foss.arm.com ([217.140.101.70]:60328 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752760AbbGFQ1f (ORCPT ); Mon, 6 Jul 2015 12:27:35 -0400 Message-ID: <559AAC73.6010105@arm.com> Date: Mon, 06 Jul 2015 17:27:31 +0100 From: Sudeep Holla User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Thomas Gleixner CC: Sudeep Holla , LKML , Ingo Molnar , Peter Zijlstra , Preeti U Murthy , Suzuki Poulose , Lorenzo Pieralisi , Catalin Marinas , "Rafael J. Wysocki" Subject: Re: [patch 1/2] tick/broadcast: Prevent deep idle states if no broadcast device available References: <20150705205032.103910828@linutronix.de> <20150705205221.724282507@linutronix.de> <559A9A2B.2030705@arm.com> <559AA256.5040305@arm.com> In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/07/15 17:06, Thomas Gleixner wrote: > On Mon, 6 Jul 2015, Sudeep Holla wrote: >> On 06/07/15 16:35, Thomas Gleixner wrote: >>> Well, we should figure out what happens while we are at it before >>> everything gets paged out again. >>> >> >> True. I just wanted to mention that this patch works for all the >> practical purposes. >> >>> In the case of CONFIG_NOHZ=n and CONFIG_HIGHRES=n the broadcast >>> hrtimer is not compiled as it depends on CONFIG_TICK_ONESHOT, so it >>> works via the bc.evtdev == NULL check. >>> >>> With either option enabled CONFIG_TICK_ONESHOT gets set, so the >>> broadcast timer gets installed but somehow does not work proper if >>> nohz and highres are disabled on the kernel command line. >>> >> >> Let me know if you want to test something to help debug this configuration. > > Can you try the following delta patch? > I just tried the failing configuration. Yes I am able to boot now, however made below 2 observations: 1. As in the case of CONFIG_HZ_PERIODIC, none of the CPUs enters deeper idle states losing local timers. So the behaviour is same in both versions of periodic mode of timer operation. 2. After boot I am seeing the below warning: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 0 at kernel/time/hrtimer.c:1247 __hrtimer_run_queues+0x148/0x150() Modules linked in: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.2.0-rc1 #573 Hardware name: ARM Juno development board (r0) (DT) Call trace: [] dump_backtrace+0x0/0x124 [] show_stack+0x10/0x1c [] dump_stack+0x84/0xc8 [] warn_slowpath_common+0x98/0xd0 [] warn_slowpath_null+0x14/0x20 [] __hrtimer_run_queues+0x144/0x150 [] hrtimer_run_queues+0xb8/0xe8 [] update_process_times+0x28/0x6c [] tick_periodic+0x3c/0xb8 [] tick_handle_periodic+0x28/0x94 [] arch_timer_handler_phys+0x28/0x38 [] handle_percpu_devid_irq+0x74/0x9c [] generic_handle_irq+0x30/0x4c [] __handle_domain_irq+0x5c/0xac [] gic_handle_irq+0x30/0x80 Exception stack(0xffffffc9768ffdb0 to 0xffffffc9768ffed0) fda0: 8c1625f8 00000008 75da4800 ffffffc9 fdc0: 768ffef0 ffffffc9 004b3448 ffffffc0 00000000 00000000 768fc000 ffffffc9 fde0: 00000000 00000000 00000001 00000000 00000002 00000000 00000000 00000000 fe00: da98d76d 001e70a3 000005dc 00000000 00000003 00000000 00000001 00000000 fe20: 00000004 00000000 00000040 00000000 ffffffff ffffffff 00000000 00000000 fe40: 008a3dd8 ffffffc0 ffffffff ffffffff 001a65a0 ffffffc0 004e2488 00000000 fe60: f7ea3080 0000007f 8c1625f8 00000008 75da4800 ffffffc9 00000000 00000000 fe80: 008da840 ffffffc0 8b7dc4e5 00000008 768fff70 ffffffc9 00884e20 ffffffc0 fea0: 005e8770 ffffffc0 00896000 ffffffc0 768fc000 ffffffc9 768ffef0 ffffffc9 fec0: 004b3408 ffffffc0 768ffef0 ffffffc9 [] el1_irq+0x64/0xd8 [] cpuidle_enter+0x14/0x20 [] call_cpuidle+0x24/0x50 [] cpu_startup_entry+0x144/0x224 [] secondary_start_kernel+0x124/0x14c ---[ end trace 87fd96b94f030e33 ]---