[Qemu-devel] Re: [PATCH 09/10] Exit loop if we have been there too long

[Avi Kivity]

On 11/30/2010 04:50 PM, Anthony Liguori wrote:
> > That's what the patch set I was alluding to did.  Or maybe I imagined 
> > the whole thing.
>
>
> No, it just split the main bitmap into three bitmaps.  I'm suggesting 
> that we have the dirty interface have two implementations, one that 
> refers to the 8-bit bitmap when TCG in use and another one that uses 
> the KVM representation.
>
> TCG really needs multiple dirty bits but KVM doesn't.  A shared 
> implementation really can't be optimal.

Live migration and the framebuffer can certainly share code with kvm and 
tcg:

- tcg or kvm maintain an internal bitmap (kvm in the kernel, tcg updates 
a private bitmap)
- a dirty log client wants to see an updated bitmap; migration on a new 
pass, vga on screen refresh
   - ask the producer (kvm or tcg) to fetch-and-clear a dirty bitmap
   - broadcast it ( |= ) into any active clients (migration or framebuffer)
- everyone's happy

The code dirty thing might need special treatment, we can have a special 
tcg-only bitmap for it.

--
error compiling committee.c: too many arguments to function