> Subject: [PATCH] netvsc: optimize stats counters performance
>
> Optimized the performance of updating the statistics counters by reducing the
> number of branches.
>
> Ordered the packet size comparisons according to the probability with typical
> internet traffic mix.
>
> Signed-off-by: Morten Brørup <m...@smartsharesystems.com>
> ---
> drivers/net/netvsc/hn_rxtx.c | 32 ++++++++++----------------------
> 1 file changed, 10 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/net/netvsc/hn_rxtx.c b/drivers/net/netvsc/hn_rxtx.c index
> 9bf1ec5509..b704b2c971 100644
> --- a/drivers/net/netvsc/hn_rxtx.c
> +++ b/drivers/net/netvsc/hn_rxtx.c
> @@ -110,30 +110,18 @@ hn_update_packet_stats(struct hn_stats *stats,
> const struct rte_mbuf *m)
> uint32_t s = m->pkt_len;
> const struct rte_ether_addr *ea;
>
> - if (s == 64) {
> - stats->size_bins[1]++;
> - } else if (s > 64 && s < 1024) {
> - uint32_t bin;
> -
> - /* count zeros, and offset into correct bin */
> - bin = (sizeof(s) * 8) - rte_clz32(s) - 5;
> - stats->size_bins[bin]++;
> - } else {
> - if (s < 64)
> - stats->size_bins[0]++;
> - else if (s < 1519)
> - stats->size_bins[6]++;
> - else
> - stats->size_bins[7]++;
> - }
> + if (s >= 1024)
> + stats->size_bins[6 + (s > 1518)]++;
> + else if (s <= 64)
> + stats->size_bins[s >> 6]++;
> + else
> + stats->size_bins[32UL - rte_clz32(s) - 5]++;
This part looks good.
>
> ea = rte_pktmbuf_mtod(m, const struct rte_ether_addr *);
> - if (rte_is_multicast_ether_addr(ea)) {
> - if (rte_is_broadcast_ether_addr(ea))
> - stats->broadcast++;
> - else
> - stats->multicast++;
> - }
> + RTE_BUILD_BUG_ON(offsetof(struct hn_stats, broadcast) !=
> + offsetof(struct hn_stats, multicast) +
> sizeof(uint64_t));
> + if (unlikely(rte_is_multicast_ether_addr(ea)))
> + (&stats->multicast)[rte_is_broadcast_ether_addr(ea)]++;
> }
This makes the code a little harder to read. How about just add "unlikely" to
rte_is_multicast_ether_addr(ea) and keep the rest unchanged?
Thank you,
Long
