> -----Original Message-----
> From: Jason Gunthorpe <jgg@xxxxxxxx>
> Sent: Friday, October 16, 2020 12:00 PM
> To: Xiong, Jianxin <jianxin.xiong@xxxxxxxxx>
> Cc: linux-rdma@xxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx; Doug Ledford <dledford@xxxxxxxxxx>; Leon Romanovsky
> <leon@xxxxxxxxxx>; Sumit Semwal <sumit.semwal@xxxxxxxxxx>; Christian Koenig <christian.koenig@xxxxxxx>; Vetter, Daniel
> <daniel.vetter@xxxxxxxxx>
> Subject: Re: [PATCH v5 1/5] RDMA/umem: Support importing dma-buf as user memory region
>
> On Thu, Oct 15, 2020 at 03:02:45PM -0700, Jianxin Xiong wrote:
>
> > +static void ib_umem_dmabuf_invalidate_cb(struct dma_buf_attachment
> > +*attach) {
> > + struct ib_umem_dmabuf *umem_dmabuf = attach->importer_priv;
> > +
> > + dma_resv_assert_held(umem_dmabuf->attach->dmabuf->resv);
> > +
> > + ib_umem_dmabuf_unmap_pages(&umem_dmabuf->umem, true);
> > + queue_work(ib_wq, &umem_dmabuf->work);
>
> Do we really want to queue remapping or should it wait until there is a page fault?
Queuing remapping here has performance advantage because it reduces the chance
of getting the page fault.
>
> What do GPUs do?
>
> Jason
