linux-kernel - Re: [PATCH] watchdog: nohz: don't run watchdog on nohz

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 31 Mar 2015 14:32:12 -0400
From:	Chris Metcalf <cmetcalf@...hip.com>
To:	Mike Galbraith <umgwanakikbuti@...il.com>,
	Don Zickus <dzickus@...hat.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Andrew Jones <drjones@...hat.com>,
	chai wen <chaiw.fnst@...fujitsu.com>,
	Ingo Molnar <mingo@...nel.org>,
	Ulrich Obergfell <uobergfe@...hat.com>,
	Fabian Frederick <fabf@...net.be>,
	Aaron Tomlin <atomlin@...hat.com>,
	Ben Zhang <benzh@...omium.org>,
	Christoph Lameter <cl@...ux.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Gilad Ben-Yossef <gilad@...yossef.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] watchdog: nohz: don't run watchdog on nohz_full cores

On 03/30/2015 10:04 PM, Mike Galbraith wrote:
> On Mon, Mar 30, 2015 at 02:51:05PM -0400, cmetcalf@...hip.com wrote:
>> From: Chris Metcalf <cmetcalf@...hip.com>
>>
>> Running watchdog can be a helpful debugging feature on regular
>> cores, but it's incompatible with nohz_full, since it forces
>> regular scheduling events.  Accordingly, just exit out immediately
>> from any nohz_full core.
> Hm, I don't see why this is needed, for debugging/testing you turn it
> on, when you set up for critical operation, you turn it off.

It can be helpful to keep the watchdog running even in production
to help diagnose hard-to-reproduce failures.  You just can't have it
running on the nohz_full cores.

-- 
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/