From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753155AbbEGHGB (ORCPT ); Thu, 7 May 2015 03:06:01 -0400 Received: from mail-gw1-out.broadcom.com ([216.31.210.62]:21015 "EHLO mail-gw1-out.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752698AbbEGHF6 (ORCPT ); Thu, 7 May 2015 03:05:58 -0400 X-IronPort-AV: E=Sophos;i="5.13,383,1427785200"; d="scan'208";a="64309905" From: "Oza (Pawandeep) Oza" To: Mike Galbraith CC: pawandeep oza , "linux-kernel@vger.kernel.org" , malayasen rout Subject: RE: [KERNEL BUG] do_timer/tick_handover_do_timer 3.10.17 Thread-Topic: [KERNEL BUG] do_timer/tick_handover_do_timer 3.10.17 Thread-Index: AQHQiCHu8BLREMfa/E6shm4qPfme451wTzoA//+dvtCAAH/VgP//ivjAgACB4oD//4ruMAAQu8oAAA53JpA= Date: Thu, 7 May 2015 07:05:56 +0000 Message-ID: <5C6899BCED92C94EBDCC00F80838E3D52113A908@SJEXCHMB06.corp.ad.broadcom.com> References: <1430968960.2955.45.camel@gmail.com> <5C6899BCED92C94EBDCC00F80838E3D52113A83F@SJEXCHMB06.corp.ad.broadcom.com> <1430975311.2955.73.camel@gmail.com> <5C6899BCED92C94EBDCC00F80838E3D52113A87B@SJEXCHMB06.corp.ad.broadcom.com> <1430978071.2955.96.camel@gmail.com> <5C6899BCED92C94EBDCC00F80838E3D52113A8D3@SJEXCHMB06.corp.ad.broadcom.com> <1430981678.2955.121.camel@gmail.com> In-Reply-To: <1430981678.2955.121.camel@gmail.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.16.203.100] Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by nfs id t477673J018087 : ) Well, I am not sure, if problem was communicated clearly from my side. Let me attempt it again. If variable tick_do_timer_cpu = 0. Things are fine. If it is some other value say for e.g. 1, 2 or 3 then core0 does not increment jiffies. (but say if it is set to tick_do_timer_cpu=1, then core1 will increment jiffies) If cpu1 ,2 and 3 are sent smp_send_stop and as a result of that cpu1, 2 and 3 will be stopped. Now only cpu0 is alive, cpu0 should increment jiffies upon each time tick. For that tick_do_timer_cpu should be set to 0. Which is not happening. Regards, -Oza -----Original Message----- From: Mike Galbraith [mailto:umgwanakikbuti@gmail.com] Sent: Thursday, May 07, 2015 12:25 PM To: Oza (Pawandeep) Oza Cc: pawandeep oza; linux-kernel@vger.kernel.org; malayasen rout Subject: Re: [KERNEL BUG] do_timer/tick_handover_do_timer 3.10.17 On Thu, 2015-05-07 at 05:58 +0000, Oza (Pawandeep) Oza wrote: > Yes. > But dying kernel doesn’t mean it CAN NOT INCREMENT jiffies. > do_timer should do the job until kernel takes its last breathe and more precisely CPU0 take its last breathe by halting itself as its last instruction. Feel free to add a redundant timer subsystem lest we BUG() in there, and whatever else you need to guarantee a perfect orderly death for your box. I prefer live boxen, would make that BUG() go away. -Mike {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I