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Re: [Qemu-devel] [PATCH 2/2] KVM: Use -cpu best as default on x86
From: |
Ryan Harper |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] KVM: Use -cpu best as default on x86 |
Date: |
Mon, 16 Jan 2012 13:46:57 -0600 |
User-agent: |
Mutt/1.5.6+20040907i |
* Alexander Graf <address@hidden> [2012-01-16 13:37]:
>
> On 16.01.2012, at 20:30, Ryan Harper wrote:
>
> > * Alexander Graf <address@hidden> [2012-01-08 17:53]:
> >> When running QEMU without -cpu parameter, the user usually wants a sane
> >> default. So far, we're using the qemu64/qemu32 CPU type, which basically
> >> means "the maximum TCG can emulate".
> >
> > it also means we all maximum possible migration targets. Have you
> > given any thought to migration with -cpu best?
>
> If you have the same boxes in your cluster, migration just works. If
> you don't, you usually use a specific CPU model that is the least
> dominator between your boxes either way.
Sure, but the idea behind -cpu best is to not have to figure that out;
you had suggested that the qemu64/qemu32 were just related to TCG, and
what I'm suggesting is that it's also the most compatible w.r.t
migration.
it sounds like if migration is a requirement, then -cpu best probably
isn't something that would be used. I suppose I'm OK with that, or at
least I don't have a better suggestion on how to carefully push up the
capabilities without at some point breaking migration.
>
> The current kvm64 type is broken. Libgmp just abort()s when we pass it
> in. So anything is better than what we do today on AMD hosts :).
I wonder if it breaks with Cyris cpus... other tools tend to do runtime
detection (mplayer).
>
>
> Alex
--
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
address@hidden
- [Qemu-devel] [PATCH 1/2] KVM: Add new -cpu best, Alexander Graf, 2012/01/08
- [Qemu-devel] [PATCH 2/2] KVM: Use -cpu best as default on x86, Alexander Graf, 2012/01/08
- Re: [Qemu-devel] [PATCH 2/2] KVM: Use -cpu best as default on x86, Ryan Harper, 2012/01/16
- Re: [Qemu-devel] [PATCH 2/2] KVM: Use -cpu best as default on x86, Alexander Graf, 2012/01/16
- Re: [Qemu-devel] [PATCH 2/2] KVM: Use -cpu best as default on x86,
Ryan Harper <=
- Re: [Qemu-devel] [PATCH 2/2] KVM: Use -cpu best as default on x86, Alexander Graf, 2012/01/16
- Re: [Qemu-devel] [PATCH 2/2] KVM: Use -cpu best as default on x86, Ryan Harper, 2012/01/16
- Re: [Qemu-devel] [PATCH 2/2] KVM: Use -cpu best as default on x86, Alexander Graf, 2012/01/16
- Re: [Qemu-devel] [PATCH 2/2] KVM: Use -cpu best as default on x86, Ryan Harper, 2012/01/16
Re: [Qemu-devel] [PATCH 1/2] KVM: Add new -cpu best, Peter Maydell, 2012/01/08
Re: [Qemu-devel] [PATCH 1/2] KVM: Add new -cpu best, Anthony Liguori, 2012/01/16