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Date: Wed, 2 Oct 2013 10:11:02 +0200
From: Stefan Hajnoczi <stefanha@gmail.com>
Message-ID: <20131002081101.GD1550@stefanha-thinkpad.redhat.com>
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Subject: Re: [Qemu-devel] KVM call minutes for 2013-10-01
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-devel qemu-devel <qemu-devel@nongnu.org>, KVM devel mailing list <kvm@vger.kernel.org>, Juan Quintela <quintela@redhat.com>

On Wed, Oct 02, 2013 at 12:17:35AM +0900, Peter Maydell wrote:
> On 1 October 2013 23:54, Juan Quintela <quintela@redhat.com> wrote:
> > - Multicore on Multicore:
> >   TCG has no locking,  no people really working there (Alex Graf?)
> 
> Apart from the TCG locking issues (which are conceptually
> tractable if anybody cares to try to fix them), the real complication
> of multicore-on-multicore is how you handle discrepancies between
> the memory models of host and guest, and in particular what
> you do if your guest has a stronger memory model than your host:
> do you insert barrier insns after every guest load/store? fall back
> to not doing mp-on-mp? something else?

If you want applications to always work then you need to insert
barriers.  It's expensive.

Stefan