[PATCH 0/2] Faster MMU lookups for Book3s v3

Alexander Graf agraf at suse.de
Thu Jul 1 20:00:37 EST 2010

Avi Kivity wrote:
> On 07/01/2010 11:18 AM, Alexander Graf wrote:
>> How does dirty bitmap flushing work on x86 atm? I loop through all
>> mapped pages and flush the ones that match the range of the region I
>> need to flush. But wouldn't it be a lot more efficient to have an
>> hlist in the memslot and loop through that when I need to flush that
>> memslot?
> x86 loops through the reverse-map link list rooted at the memory
> slot.  The linked list links all sptes for a single hva.
> So, it's like you describe, except it's an array of lists instead of a
> single list.  We need per-page rmap lists to be able to remove a
> page's sptes in response to an mmu notifier callback, and to be able
> to write protect a guest page if it's used as a page table.

But doesn't that mean that you still need to loop through all the hvas
that you want to invalidate? Wouldn't it speed up dirty bitmap flushing
a lot if we'd just have a simple linked list of all sPTEs belonging to
that memslot?


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