[dpdk-dev] [PATCH] dmadev: introduce DMA device library

[Jerin Jacob]

On Mon, Jul 12, 2021 at 12:31 PM Morten Brørup <mb at smartsharesystems.com> wrote:
>
> > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Jerin Jacob
>
> > Probably we can remove rte_dmadev_fill_sg() variant and keep sg only
> > for copy to save 8B.
>
> Perhaps the scatter/gather functions can be on a separate cache line, following the cache line with the simple functions?
> Of course, this is only beneficial if the SG functions are not used with simple functions.
> This means that we reserve space for 8 simple functions and 8 SG functions.

Currently, there are only two SG and normal ops functions. IMO, should
be to keep all fastpath functions in the same CL irrespective of it is
simple or not.
My suggestion was more like, if there is no HW support for
rte_dmadev_fill_sg() we can remove it from spec.

>
> And if one or two functions are used with both simple and SG functions, it/they can be present in both cache lines. (This is somewhat dirty, but would be a typical implementation for a DPDK flow data structure.)
>
> -Morten