Re: [PATCH] net/i40e: Fast release optimizations

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, Jun 24, 2025 at 06:12:38AM +0000, Morten Brørup wrote:
> When fast releasing mbufs, the mbufs are not accessed, so do not prefetch
> them.
> This saves a mbuf load operation for each fast released TX mbuf.
> 
> When fast release of mbufs is enabled for a TX queue, cache the mbuf
> mempool pointer in the TX queue structure.
> This saves one mbuf load operation for each burst of fast released TX
> mbufs.
> 
> The txep->mbuf pointer is not used after the mbuf has been freed, so do
> not reset the pointer.
> This saves a txep store operation for each TX mbuf freed.
> 
> Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
> ---
>  drivers/net/intel/common/tx.h                 |  5 +++
>  .../i40e/i40e_recycle_mbufs_vec_common.c      |  4 +-
>  drivers/net/intel/i40e/i40e_rxtx.c            | 39 ++++++++++---------
>  3 files changed, 28 insertions(+), 20 deletions(-)
> 
Thanks, Morten. This optimization probably applies other places in our
drivers too. I'll look at this patch - and where else it can apply - for
25.11, since we are nearing the end of the 25.07 release cycle.

/Bruce