Re: [PATCH] mm/gup: restore the ability to pin more than 2GB at a time

[John Hubbard]

On 10/30/24 5:04 AM, Jason Gunthorpe wrote:
> On Wed, Oct 30, 2024 at 09:34:51AM +0100, David Hildenbrand wrote:
>
> > The unusual thing is not the amount of system memory we are pinning but *how
> > many* pages we try pinning in the single call.
> >
> > If you stare at vfio_pin_pages_remote, we seem to be batching it.
> >
> > long req_pages = min_t(long, npage, batch->capacity);
> >
> > Which is
> >
> > #define VFIO_BATCH_MAX_CAPACITY (PAGE_SIZE / sizeof(struct page *))
> >
> > So you can fix this in your driver ;)
>
> Yeah, everything batches that I'm aware of. RDMA also uses a 4k batch
> size, and iommufd uses 64k.
>
> Jason

Yes. It's a surprise, but the driver can do that.


thanks,
--
John Hubbard