Date: Thu, 29 Jan 2009 17:03:35 +0100
From: Frank Mehnert <Frank.Mehnert@Sun.COM>
Subject: Re: PFs on pages pinned with get_user_pages()
In-reply-to: <1233240757.4495.94.camel@laptop>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, Avi Kivity <avi@redhat.com>,
       Ingo Molnar <mingo@elte.hu>
Message-id: <200901291703.35463.frank.mehnert@sun.com>
Organization: Sun Microsystems
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On Thursday 29 January 2009, Peter Zijlstra wrote:
> > > That aside, is there any reason you have to avoid scheduling? Otherwi=
se
> > > I would just allow so and be done with it.
> >
> > The reason is that our code expects that to ensure syncing of the CPU
> > state with the saved state. I fear it is quite difficult to change
> > that...
>
> Ah, is that what KVM uses the preempt notifiers for? Could you too?

Right, that could be an option.

We will try to change our code which is a big effort as we try
to keep the code as unique as possible between the different
hosts we support (Linux, Solaris, Windows, Mac OS X).

Just to be sure: There is no other option than disabling interrupts
or calling disable_preemption() to prevent scheduling?

Kind regards,

=46rank
=2D-=20
Dr.-Ing. Frank Mehnert    Sun Microsystems    http://www.sun.com/

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