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Date: Wed, 20 Mar 2013 17:55:15 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] [RFC PATCH RDMA support v4: 03/10] more verbose
 documentation of the RDMA transport
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To: "Michael R. Hines" <mrhines@linux.vnet.ibm.com>
Cc: aliguori@us.ibm.com, qemu-devel@nongnu.org, owasserm@redhat.com, abali@us.ibm.com, mrhines@us.ibm.com, gokul@us.ibm.com, Paolo Bonzini <pbonzini@redhat.com>

On Wed, Mar 20, 2013 at 11:15:48AM -0400, Michael R. Hines wrote:
> OK, can we make a deal? =)
> 
> I'm willing to put in the work to perform the dynamic registration
> on the destination side,
> but let's go a step further and piggy-back on the effort:
> 
> We need to couple this registration with a very small modification
> to save_ram_block():
> 
> Currently, save_ram_block does:
> 
> 1. is RDMA turned on?      if yes, unconditionally add to next chunk
>                                          (will be made to
> dynamically register on destination)
> 2. is_dup_page() ?            if yes, skip
> 3. in xbzrle cache?           if yes, skip
> 4. still not sent?                if yes, transmit
> 
> I propose adding a "stub" function that adds:
> 
> 0. is page mapped?         if yes, skip   (always returns true for now)
> 1. same
> 2. same
> 3. same
> 4. same
> 
> Then, later, in a separate patch, I can implement /dev/pagemap support.
> 
> When that's done, RDMA dynamic registration will actually take effect and
> benefit from actually verifying that the page is mapped or not.
> 
> - Michael

Mapped into guest? You mean e.g. for ballooning?