Re: [RFC 00/11] THP support for zone device pages

[Balbir Singh <balbirs@nvidia.com>]

On 7/5/25 02:17, Zi Yan wrote:
> On 4 Jul 2025, at 9:52, Francois Dugast wrote:
> 
>> Hi,
>>
>> On Fri, Mar 07, 2025 at 10:20:30AM +1100, Balbir Singh wrote:
>>> On 3/7/25 10:08, Matthew Brost wrote:
>>>> On Thu, Mar 06, 2025 at 03:42:28PM +1100, Balbir Singh wrote:
>>>>
>>>> This is an exciting series to see. As of today, we have just merged this
>>>> series into the DRM subsystem / Xe [2], which adds very basic SVM
>>>> support. One of the performance bottlenecks we quickly identified was
>>>> the lack of THP for device pages—I believe our profiling showed that 96%
>>>> of the time spent on 2M page GPU faults was within the migrate_vma_*
>>>> functions. Presumably, this will help significantly.
>>>>
>>>> We will likely attempt to pull this code into GPU SVM / Xe fairly soon.
>>>> I believe we will encounter a conflict since [2] includes these patches
>>>> [3] [4], but we should be able to resolve that. These patches might make
>>>> it into the 6.15 PR — TBD but I can get back to you on that.
>>>>
>>>> I have one question—does this series contain all the required core MM
>>>> changes for us to give it a try? That is, do I need to include any other
>>>> code from the list to test this out?
>>>>
>>>
>>> Thank you, the patches are built on top of mm-everything-2025-03-04-05-51, which
>>> includes changes by Alistair to fix fs/dax reference counting and changes
>>> By Zi Yan (folio split changes), the series builds on top of those, but the
>>> patches are not dependent on the folio split changes, IIRC
>>>
>>> Please do report bugs/issues that you come across.
>>>
>>> Balbir
>>>
>>
>> Thanks for sharing. We used your series to experimentally enable THP migration
>> of zone device pages in DRM GPU SVM and Xe. Here is an early draft [1] rebased
>> on 6.16-rc1. It is still hacky but I wanted to share some findings/questions:
>> - Is there an updated version of your series?
> 
> Here is a new one: https://lore.kernel.org/linux-mm/20250703233511.2028395-1-balbirs@nvidia.com/.

Thanks Zi!

Could you please try out the latest patches Francois?

Balbir