On 4/15/19 11:09 AM, Feng Li wrote:
> Hi Jens,
>
> I'm interested in the io_uring, and have a doubt about it.
> If I setup io_uring with IORING_REGISTER_BUFFERS,
> the kernel doesn't need copy data from user space to the kernel, right?
> Does it mean this is a zero-copy feature?
Doesn't it depends on the definition of 'copy'?
There is still a copy from original userspace pages to the registered buffer?
Dongli Zhang
>
> From the code, kernel directly get the userspace virtual address's
> pages and store them:
>
> 2475 pret = get_user_pages_longterm(ubuf, nr_pages, FOLL_WRITE,
> 2476 pages, vmas);
>
>
>
