Re: [Xen-devel] [PATCH v2 0/4] xen: enable EPT A/D bit feature

[Tim Deegan <tim@xxxxxxx>]

At 09:57 +0800 on 20 Jun (1340186263), Xudong Hao wrote:
> Changes from v1:
> - Move hap_has_dirty_bit and hap_has_access_bit definition from patch 3 to 
> patch2.
> - define them as bool_t instead of int.
> 
> Extended Page Tables introduce two bit: access bit and dirty bit, A/D bits
> enable VMMs to efficiently implement memory management and page classification
> algorithms to optimize VM memory operations.
> 
> This series of patches enable EPT dirty bit feature for guest live migration.

Thanks for this.  I have a few high-level questions:

- You're proposing this for after 4.2, right?

- Have you measured what difference this makes?  I take it it improves
  performance during live migration but it would be good to know how much
  before taking on extra code.

- Is this intended to replace the old log-dirty mechanism for vram
  tracking as well?  It looks like it does that, but the description
  doesn't mention it. 

I'll be reviewing te patches in more detail later in the week. 

Cheers,

Tim.

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