Re: [PATCH][RFC]: pte notifiers -- support for external page tables

Avi Kivity
2007-09-05T20:42:26Z

[resend due to broken cc list in my original post]

Jack Steiner wrote:
> On Wed, Sep 05, 2007 at 07:38:48PM +0300, Avi Kivity wrote:
>
>> Some hardware and software systems maintain page tables outside the normal
>> Linux page tables, which reference userspace memory. This includes
>> Infiniband, other RDMA-capable devices, and kvm (with a pending patch).
>>
>>
>
> I like it.
>
> We have 2 special devices with external TLBs that can
> take advantage of this.
>
> One suggestion - at least for what we need. Can the notifier be
> registered against the mm_struct instead of (or in addition to) the
> vma?
>

Yes. It's a lot simpler since this way we don't have to support vma
creation/splitting/merging/destruction. There's a tiny performance hit
for kvm, but it isn't worth the bother.

Will implement for v2 of this patch.

--
Any sufficiently difficult bug is indistinguishable from a feature.