[v4] virtio: optimize stats counters performance
Checks
Commit Message
Optimized the performance of updating the virtio statistics counters by
reducing the number of branches and inlining the function.
Ordered the packet size comparisons according to the probability with
typical internet traffic mix.
Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
---
v4:
* Consider multicast/broadcast packets unlikely.
v3:
* Eliminated a local variable.
* Note: Substituted sizeof(uint32_t)*4 by 32UL, using unsigned long type
to keep optimal offsetting in generated assembler output.
* Removed unnecessary curly braces.
v2:
* Fixed checkpatch warning about line length.
---
drivers/net/virtio/virtio_rxtx.c | 34 --------------------------------
drivers/net/virtio/virtio_rxtx.h | 23 +++++++++++++++++++--
2 files changed, 21 insertions(+), 36 deletions(-)
Comments
On Wed, 31 Jul 2024 22:58:16 +0000
Morten Brørup <mb@smartsharesystems.com> wrote:
> +
> +static inline void
> +virtio_update_packet_stats(struct virtnet_stats *const stats, const struct rte_mbuf *const mbuf)
> +{
> + uint32_t s = mbuf->pkt_len;
> + const struct rte_ether_addr *ea = rte_pktmbuf_mtod(mbuf, const struct rte_ether_addr *);
> +
> + stats->bytes += s;
> +
> + 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]++;
> +
> + RTE_BUILD_BUG_ON(offsetof(struct virtnet_stats, broadcast) !=
> + offsetof(struct virtnet_stats, multicast) + sizeof(uint64_t));
> + if (unlikely(rte_is_multicast_ether_addr(ea)))
> + (&stats->multicast)[rte_is_broadcast_ether_addr(ea)]++;
> +}
>
Why move it to virtio_rxtx.h it was fine where it was.
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Thursday, 1 August 2024 01.46
>
> On Wed, 31 Jul 2024 22:58:16 +0000
> Morten Brørup <mb@smartsharesystems.com> wrote:
>
> > +
> > +static inline void
> > +virtio_update_packet_stats(struct virtnet_stats *const stats, const
> struct rte_mbuf *const mbuf)
> > +{
> > + uint32_t s = mbuf->pkt_len;
> > + const struct rte_ether_addr *ea = rte_pktmbuf_mtod(mbuf, const
> struct rte_ether_addr *);
> > +
> > + stats->bytes += s;
> > +
> > + 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]++;
> > +
> > + RTE_BUILD_BUG_ON(offsetof(struct virtnet_stats, broadcast) !=
> > + offsetof(struct virtnet_stats, multicast) +
> sizeof(uint64_t));
> > + if (unlikely(rte_is_multicast_ether_addr(ea)))
> > + (&stats->multicast)[rte_is_broadcast_ether_addr(ea)]++;
> > +}
> >
>
> Why move it to virtio_rxtx.h it was fine where it was.
Because it is also called from the vector implementations [1], where it was not inlined before.
[1]: https://elixir.bootlin.com/dpdk/v24.07/A/ident/virtio_update_packet_stats
@@ -81,40 +81,6 @@ vq_ring_free_chain(struct virtqueue *vq, uint16_t desc_idx)
dp->next = VQ_RING_DESC_CHAIN_END;
}
-void
-virtio_update_packet_stats(struct virtnet_stats *stats, struct rte_mbuf *mbuf)
-{
- uint32_t s = mbuf->pkt_len;
- struct rte_ether_addr *ea;
-
- stats->bytes += s;
-
- 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]++;
- }
-
- ea = rte_pktmbuf_mtod(mbuf, struct rte_ether_addr *);
- if (rte_is_multicast_ether_addr(ea)) {
- if (rte_is_broadcast_ether_addr(ea))
- stats->broadcast++;
- else
- stats->multicast++;
- }
-}
-
static inline void
virtio_rx_stats_updated(struct virtnet_rx *rxvq, struct rte_mbuf *m)
{
@@ -35,7 +35,26 @@ struct virtnet_tx {
};
int virtio_rxq_vec_setup(struct virtnet_rx *rxvq);
-void virtio_update_packet_stats(struct virtnet_stats *stats,
- struct rte_mbuf *mbuf);
+
+static inline void
+virtio_update_packet_stats(struct virtnet_stats *const stats, const struct rte_mbuf *const mbuf)
+{
+ uint32_t s = mbuf->pkt_len;
+ const struct rte_ether_addr *ea = rte_pktmbuf_mtod(mbuf, const struct rte_ether_addr *);
+
+ stats->bytes += s;
+
+ 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]++;
+
+ RTE_BUILD_BUG_ON(offsetof(struct virtnet_stats, broadcast) !=
+ offsetof(struct virtnet_stats, multicast) + sizeof(uint64_t));
+ if (unlikely(rte_is_multicast_ether_addr(ea)))
+ (&stats->multicast)[rte_is_broadcast_ether_addr(ea)]++;
+}
#endif /* _VIRTIO_RXTX_H_ */