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From: Prarit Bhargava <prarit@redhat.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	virtualization@lists.osdl.org, Ingo Molnar <mingo@elte.hu>,
	Thomas Gleixner <tglx@linutronix.de>,
	john stultz <johnstul@us.ibm.com>,
	Zachary Amsden <zach@vmware.com>,
	James Morris <jmorris@namei.org>, Dan Hecht <dhecht@vmware.com>,
	Paul Mackerras <paulus@samba.org>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Chris Lalancette <clalance@redhat.com>,
	Rick Lindsley <ricklind@us.ibm.com>
Subject: Re: [patch 1/2] Ignore stolen time in the softlockup watchdog
Date: Tue, 27 Mar 2007 12:53:22 -0400	[thread overview]
Message-ID: <46094C02.9050702@redhat.com> (raw)
In-Reply-To: <46094861.7080400@goop.org>



Jeremy Fitzhardinge wrote:
> Prarit Bhargava wrote:
>   
>> I'd like to see this patch implement/fix touch_cpu_softlockup_watchdog
>> and touch_softlockup_watchdog to mimic touch_nmi_watchdog's behaviour.
>>     
>
> Why?  Is that more correct?  It seems to me that you're interested in
> whether a specific CPU has gone and locked up.  If touching the watchdog
>   
> makes it update all CPU timestamps, then you'll hide the fact that other
> CPUs have locked up, won't it?
>
>   
In case of misuse, yes.  But there are cases where we know that all CPUs 
will have softlockup issues, such as when doing a "big" sysrq-t dump.  
When doing the sysrq-t we take the tasklist_lock which prevents all 
other CPUs from scheduling -- this leads to bogus softlockup messages, 
so we need to reset everyone's watchdog just before releasing the 
tasklist_lock.

Another question -- are you going to expose disable/enable_watchdog to 
other subsystems?  Or are you going to expose touch_softlockup_watchdog?

>     J
>   

WARNING: multiple messages have this Message-ID (diff)
From: Prarit Bhargava <prarit@redhat.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Rick Lindsley <ricklind@us.ibm.com>,
	john stultz <johnstul@us.ibm.com>, Ingo Molnar <mingo@elte.hu>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	virtualization@lists.osdl.org, Paul Mackerras <paulus@samba.org>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [patch 1/2] Ignore stolen time in the softlockup watchdog
Date: Tue, 27 Mar 2007 12:53:22 -0400	[thread overview]
Message-ID: <46094C02.9050702@redhat.com> (raw)
In-Reply-To: <46094861.7080400@goop.org>



Jeremy Fitzhardinge wrote:
> Prarit Bhargava wrote:
>   
>> I'd like to see this patch implement/fix touch_cpu_softlockup_watchdog
>> and touch_softlockup_watchdog to mimic touch_nmi_watchdog's behaviour.
>>     
>
> Why?  Is that more correct?  It seems to me that you're interested in
> whether a specific CPU has gone and locked up.  If touching the watchdog
>   
> makes it update all CPU timestamps, then you'll hide the fact that other
> CPUs have locked up, won't it?
>
>   
In case of misuse, yes.  But there are cases where we know that all CPUs 
will have softlockup issues, such as when doing a "big" sysrq-t dump.  
When doing the sysrq-t we take the tasklist_lock which prevents all 
other CPUs from scheduling -- this leads to bogus softlockup messages, 
so we need to reset everyone's watchdog just before releasing the 
tasklist_lock.

Another question -- are you going to expose disable/enable_watchdog to 
other subsystems?  Or are you going to expose touch_softlockup_watchdog?

>     J
>   

  reply	other threads:[~2007-03-27 16:54 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-27  5:38 [patch 0/2] softlockup watchdog improvements Jeremy Fitzhardinge
2007-03-27  5:38 ` Jeremy Fitzhardinge
2007-03-27  5:38 ` [patch 1/2] Ignore stolen time in the softlockup watchdog Jeremy Fitzhardinge
2007-03-27  7:00   ` Eric Dumazet
2007-03-27  7:12     ` Jeremy Fitzhardinge
2007-03-27  7:12       ` Jeremy Fitzhardinge
2007-03-27  7:50       ` Eric Dumazet
2007-03-27  7:50         ` Eric Dumazet
2007-03-27 14:39   ` Prarit Bhargava
2007-03-27 14:39     ` Prarit Bhargava
2007-03-27 16:37     ` Jeremy Fitzhardinge
2007-03-27 16:53       ` Prarit Bhargava [this message]
2007-03-27 16:53         ` Prarit Bhargava
2007-03-27 17:10         ` Jeremy Fitzhardinge
2007-03-27 17:10           ` Jeremy Fitzhardinge
2007-03-27 17:20           ` Prarit Bhargava
2007-03-27 17:20             ` Prarit Bhargava
2007-03-27  5:38 ` [patch 2/2] percpu enable flag for " Jeremy Fitzhardinge
2007-03-27  5:38   ` Jeremy Fitzhardinge
2007-03-27 14:42   ` Prarit Bhargava
2007-03-27 14:42     ` Prarit Bhargava

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