[dpdk-dev] [PATCH v2] net/mlx5: support metadata as flow rule criteria
Yongseok Koh
yskoh at mellanox.com
Wed Oct 3 09:22:41 CEST 2018
> On Oct 2, 2018, at 10:22 PM, Dekel Peled <dekelp at mellanox.com> wrote:
>
>>> @@ -137,8 +152,10 @@
>>> n = RTE_MIN((uint16_t)(pkts_n - nb_tx),
>> MLX5_VPMD_TX_MAX_BURST);
>>> if (txq->offloads & DEV_TX_OFFLOAD_MULTI_SEGS)
>>> n = txq_count_contig_single_seg(&pkts[nb_tx], n);
>>> - if (txq->offloads & MLX5_VEC_TX_CKSUM_OFFLOAD_CAP)
>>> - n = txq_calc_offload(&pkts[nb_tx], n, &cs_flags);
>>> + if (txq->offloads & (MLX5_VEC_TX_CKSUM_OFFLOAD_CAP |
>>> + DEV_TX_OFFLOAD_MATCH_METADATA))
>>
>> How about writing a separate func - txq_count_contig_same_metadata()?
>> And it would be better to rename txq_calc_offload() to
>> txq_count_contig_same_csflag().
>> Then, there could be less redundant if-clause in the funcs.
>
> It was considered during implementation but decided to handle all related logic
> In same function.
But it doesn't look efficient. Note that it is performance critical datapath.
if (A) {
for (n)
do_a();
}
if (B) {
for (n)
do_b();
}
vs.
if (A or B) {
for (n) {
if (A)
do_a();
if (B)
do_b();
}
}
In the worst case, condition A and B will be checked n times each while it can be
only once in the first case.
Thanks,
Yongseok
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