On 6/30/2021 3:45 AM, Min Hu (Connor) wrote:
> Hi, all
> one question about 'rxm->hash.rss' and 'mb->hash.fdir'.
>
> In Rx recv packets function,
> 'rxm->hash.rss' will report rss hash result from Rx desc.
> 'rxm->hash.fdir' will report filter identifier from Rx desc.
>
> But function implementation differs from some PMDs. for example:
> i40e, MLX5 report the two at the same time if pkt_flags is set,like:
> ******************************************
> if (pkt_flags & PKT_RX_RSS_HASH) {
> rxm->hash.rss =
> rte_le_to_cpu_32(rxd.wb.qword0.hi_dword.rss);
> }
> if (pkt_flags & PKT_RX_FDIR) {
> mb->hash.fdir.hi =
> rte_le_to_cpu_32(rxdp->wb.qword3.hi_dword.fd_id);
> }
> ********************************************
>
> While, ixgbe only report one of the two. like:
> ******************************************
> if (likely(pkt_flags & PKT_RX_RSS_HASH))
> mb->hash.rss = rte_le_to_cpu_32(
> rxdp[j].wb.lower.hi_dword.rss);
> else if (pkt_flags & PKT_RX_FDIR) {
> mb->hash.fdir.hash = rte_le_to_cpu_16(
> rxdp[j].wb.lower.hi_dword.csum_ip.csum) &
> IXGBE_ATR_HASH_MASK;
> mb->hash.fdir.id = rte_le_to_cpu_16(
> rxdp[j].wb.lower.hi_dword.csum_ip.ip_id);
> }
> ********************************************
> So, what is application scenario for 'rxm->hash.rss' and 'mb->hash.fdir',
> that is, why the two should be reported? How about reporting the two at the
> same
> time?
> Thanks for your reply.
Hi Connor,
mbuf->hash is union, so it is not possible to set both 'hash.rss' & 'hash.fdir'.
I assume for i40e & mlx5 case 'pkt_flags' indicate which one is valid and only
one is set in practice. Cc'ed driver mainteriners for more comment.
