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

From: Jason Wang
Date: Tue Jun 29 2021 - 03:34:06 EST

在 2021/6/29 下午2:40, Yongji Xie 写道:
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.


We probably can use umem for memory other than the virtqueue (still via mmap()).