Re: [PATCH v2 2/3] mm/hmm: allow snapshot of the special zero page

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Tue, Oct 22, 2019 at 05:41:11PM +0000, Jason Gunthorpe wrote:
> On Tue, Oct 22, 2019 at 01:30:26PM -0400, Jerome Glisse wrote:
> 
> > > Smart drivers can test somehow for pfn == zero_page and optimize?
> > 
> > There is nothing to optimize here, i do not know any hardware that
> > have a special page table entry that make all memory access return
> > zero.
> 
> Presumably any GPU could globally dedicate one page of internal memory
> as a zero page and remap CPU zero page to that internal memory page?
> This is basically how the CPU zero page works.

Yes that would work too but i do not know of any upstream driver
that does that.

> I suspect mlx5 could do the same with its internal memory, but the
> internal memory is too limited to make this worth while.
> 
> mlx5 also has a specially 'zero MR' that always reads as zero (and
> discards writes), but it doesn't quite fit well into the ODP flow.

Well you can always ask for new stuff to your beloved hardware
engineers, they never say no right ? :)

Cheers,
Jérôme






[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux