Re: [RFC][PATCH] qemu-kvm: Introduce writeback scope for cpu_synchronize_state

[Avi Kivity <avi@redhat.com>]

On 11/16/2009 07:00 PM, Jan Kiszka wrote:
> This patch aims at addressing the mp_state writeback issue in a cleaner
> fashion.

What's the issue?  the fact that mp_state is updated whenever state is 
synchronized, while it could be simultaneously updated from other vcpus 
(which latter updates are then lost)?

> By introducing additional information about the scope of the
> scheduled vcpu state writeback, we can simply skin mp_state (and maybe
> other specific states in the future) when updating the in-kernel state.
>
> The writeback scope is defined when calling cpu_synchronize_state. It
> accumulated, ie. once a full writeback was requested, this will stick
> until it was performed.
>    

Maybe it's just simpler to divorce mp_state from the rest of the state.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.