Re: [PATCH v1 2/3] io: Add zerocopy and errqueue

[Leonardo Bras Soares Passos]

On Tue, Sep 7, 2021 at 1:44 PM Peter Xu <peterx@redhat.com> wrote:
>
> On Thu, Sep 02, 2021 at 03:59:25AM -0300, Leonardo Bras Soares Passos wrote:
> > I also suggested something like that, but I thought it could be good if we 
> > could
> > fall back to io_writev() if we didn't have the zerocopy feature (or
> > the async feature).
> >
> > What do you think?
>
> That fallback looks safe and ok, I'm just not sure whether it'll be of great
> help.  E.g. if we provide an QIO api that allows both sync write and zero-copy
> write (then we do the fallback when necessary), it means the buffer 
> implication
> applies too to this api, so it's easier to me to just detect the zero copy
> capability and use one alternative.  Thanks,
>
> --
> Peter Xu
>

I was thinking this way (async method with fallback) we would allow code using
the QIO api to just try to use the io_async_writev() whenever the code
seems fit, and
let the QIO channel layer to decide when it can be used
(implementation provides,
features available), and just fallback to io_writev() when it can't be used.

Best regards,
Leo