Hi Tyler,
Few comments below.
On Fri, Jun 02, 2023 at 12:45:07PM -0700, Tyler Retzlaff wrote:
> Replace the use of rte_atomic.h types and functions, instead use GCC
> supplied C++11 memory model builtins.
>
> Signed-off-by: Tyler Retzlaff <roret...@linux.microsoft.com>
> Acked-by: Morten Brørup <m...@smartsharesystems.com>
> Acked-by: Bruce Richardson <bruce.richard...@intel.com>
> ---
> drivers/net/ring/rte_eth_ring.c | 26 ++++++++++++++++----------
> 1 file changed, 16 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/net/ring/rte_eth_ring.c b/drivers/net/ring/rte_eth_ring.c
> index e8bc9b6..43eb627 100644
> --- a/drivers/net/ring/rte_eth_ring.c
> +++ b/drivers/net/ring/rte_eth_ring.c
> @@ -44,8 +44,8 @@ enum dev_action {
>
> struct ring_queue {
> struct rte_ring *rng;
> - rte_atomic64_t rx_pkts;
> - rte_atomic64_t tx_pkts;
> + uint64_t rx_pkts;
> + uint64_t tx_pkts;
> };
>
> struct pmd_internals {
> @@ -80,9 +80,10 @@ struct pmd_internals {
> const uint16_t nb_rx = (uint16_t)rte_ring_dequeue_burst(r->rng,
> ptrs, nb_bufs, NULL);
> if (r->rng->flags & RING_F_SC_DEQ)
> - r->rx_pkts.cnt += nb_rx;
> + r->rx_pkts += nb_rx;
> else
> - rte_atomic64_add(&(r->rx_pkts), nb_rx);
> + /* NOTE: review for potential ordering optimization */
> + __atomic_fetch_add(&r->rx_pkts, nb_rx, __ATOMIC_SEQ_CST);
We can use __ATOMIC_RELAXED here (and below too), since there is no ordering
constraint. We only want statistics to be correct.
You can remove the other NOTEs from the patch.
> return nb_rx;
> }
>
> @@ -94,9 +95,10 @@ struct pmd_internals {
> const uint16_t nb_tx = (uint16_t)rte_ring_enqueue_burst(r->rng,
> ptrs, nb_bufs, NULL);
> if (r->rng->flags & RING_F_SP_ENQ)
> - r->tx_pkts.cnt += nb_tx;
> + r->tx_pkts += nb_tx;
> else
> - rte_atomic64_add(&(r->tx_pkts), nb_tx);
> + /* NOTE: review for potential ordering optimization */
> + __atomic_fetch_add(&r->tx_pkts, nb_tx, __ATOMIC_SEQ_CST);
> return nb_tx;
> }
>
> @@ -184,13 +186,15 @@ struct pmd_internals {
>
> for (i = 0; i < RTE_ETHDEV_QUEUE_STAT_CNTRS &&
> i < dev->data->nb_rx_queues; i++) {
> - stats->q_ipackets[i] = internal->rx_ring_queues[i].rx_pkts.cnt;
> + /* NOTE: review for atomic access */
> + stats->q_ipackets[i] = internal->rx_ring_queues[i].rx_pkts;
> rx_total += stats->q_ipackets[i];
> }
>
> for (i = 0; i < RTE_ETHDEV_QUEUE_STAT_CNTRS &&
> i < dev->data->nb_tx_queues; i++) {
> - stats->q_opackets[i] = internal->tx_ring_queues[i].tx_pkts.cnt;
> + /* NOTE: review for atomic access */
> + stats->q_opackets[i] = internal->tx_ring_queues[i].tx_pkts;
> tx_total += stats->q_opackets[i];
> }
>
> @@ -207,9 +211,11 @@ struct pmd_internals {
> struct pmd_internals *internal = dev->data->dev_private;
>
> for (i = 0; i < dev->data->nb_rx_queues; i++)
> - internal->rx_ring_queues[i].rx_pkts.cnt = 0;
> + /* NOTE: review for atomic access */
> + internal->rx_ring_queues[i].rx_pkts = 0;
> for (i = 0; i < dev->data->nb_tx_queues; i++)
> - internal->tx_ring_queues[i].tx_pkts.cnt = 0;
> + /* NOTE: review for atomic access */
> + internal->tx_ring_queues[i].tx_pkts = 0;
>
> return 0;
> }
> --
> 1.8.3.1
>
