Re: Re: [PATCH v8 00/10] Introduce VDUSE - vDPA Device in Userspace

[Yongji Xie]

On Tue, Jun 29, 2021 at 12:13 PM Jason Wang <jasowang@xxxxxxxxxx> wrote:
>
>
> 在 2021/6/28 下午6:32, Yongji Xie 写道:
> >> The large barrier is bounce-buffer mapping: SPDK requires hugepages
> >> for NVMe over PCIe and RDMA, so take some preallcoated hugepages to
> >> map as bounce buffer is necessary. Or it's hard to avoid an extra
> >> memcpy from bounce-buffer to hugepage.
> >> If you can add an option to map hugepages as bounce-buffer,
> >> then SPDK could also be a potential user of vduse.
> >>
> > I think we can support registering user space memory for bounce-buffer
> > use like XDP does. But this needs to pin the pages, so I didn't
> > consider it in this initial version.
> >
>
> Note that userspace should be unaware of the existence of the bounce buffer.
>

If so, it might be hard to use umem. Because we can't use umem for
coherent mapping which needs physical address contiguous space.

Thanks,
Yongji