linux-kernel - Re: [PATCH 0/5 V5] Avoid soft lockup message when KVM is stopped by host

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Message-ID: <20111214145407.GA4075@mgebm.net>
Date:	Wed, 14 Dec 2011 09:54:07 -0500
From:	Eric B Munson <emunson@...bm.net>
To:	Avi Kivity <avi@...hat.com>
Cc:	Marcelo Tosatti <mtosatti@...hat.com>, mingo@...hat.com,
	hpa@...or.com, arnd@...db.de, ryanh@...ux.vnet.ibm.com,
	aliguori@...ibm.com, jeremy.fitzhardinge@...rix.com,
	levinsasha928@...il.com, Jan Kiszka <jan.kiszka@...mens.com>,
	kvm@...r.kernel.org, linux-arch@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/5 V5] Avoid soft lockup message when KVM is stopped by
 host

On Wed, 14 Dec 2011, Avi Kivity wrote:

> On 12/14/2011 02:16 PM, Marcelo Tosatti wrote:
> > > Having this controlled from userspace means it doesn't work for SIGSTOP
> > > or for long scheduling delays.  What about doing this automatically
> > > based on preempt notifiers?
> >
> > Long scheduling delays should be considered hangups from the guest
> > perspective.
> 
> Why?  To the guest it looks like slow hardware, but it will interpret it
> as a softlockup.
> 
> > About SIGSTOP, that is a corner case. Unsure if its even properly supported 
> > by QEMU.
> 
> It works from my experience.
> 
> -- 
> error compiling committee.c: too many arguments to function
> 

And if the soft lockup warning is a concern here, we can have a SIGCONT handler
set the flag the same way qemu stop/cont does.

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