Re: [PATCH v2] eal/x86: optimize memcpy of small sizes

Stephen Hemminger
2025-11-21T17:12:06Z

On Fri, 21 Nov 2025 17:02:17 +0000
Bruce Richardson <bruce.richardson@intel.com> wrote:

> > As I have said before would rather that DPDK move away from having its
> > own specialized memcpy. How is this compared to stock inline gcc?
> > The main motivation is that the glibc/gcc team does more testing across
> > multiple architectures and has a community with more expertise on CPU
> > special cases.
>
> I would tend to agree. Even if we get rte_memcpy a few cycles faster, I
> suspect many apps wouldn't notice the difference. However, I understand
> that the virtio/vhost libraries gain from using rte_memcpy over standard
> memcpy - or at least used to. Perhaps we can consider deprecating
> rte_memcpy and just putting a vhost-specific memcpy in that library?

It would be good to figure out why vhost is better with rte_memcpy,
maybe there is some alignment assumption that is in one and not the other?