The 05/24/2023 14:22, Haiyang Zhang wrote:
Hi Haiyang,
>
> The apc->eth_stats.rx_cqes is one per NIC (vport), and it's on the
> frequent and parallel code path of all queues. So, r/w into this
> single shared variable by many threads on different CPUs creates a
> lot caching and memory overhead, hence perf regression. And, it's
> not accurate due to the high volume concurrent r/w.
Do you have any numbers to show the improvement of this change?
>
> Since the error path of mana_poll_rx_cq() already has warnings, so
> keeping the counter and convert it to a per-queue variable is not
> necessary. So, just remove this counter from this high frequency
> code path.
>
> Also, remove the tx_cqes counter for the same reason. We have
> warnings & other counters for errors on that path, and don't need
> to count every normal cqe processing.
Will you not have problems with the counter 'apc->eth_stats.tx_cqe_err'?
It is not in the hot path but you will have concurrent access to it.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: bd7fc6e1957c ("net: mana: Add new MANA VF performance counters for easier troubleshooting")
> Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> ---
> drivers/net/ethernet/microsoft/mana/mana_en.c | 10 ----------
> drivers/net/ethernet/microsoft/mana/mana_ethtool.c | 2 --
> include/net/mana/mana.h | 2 --
> 3 files changed, 14 deletions(-)
>
> diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
> index 06d6292e09b3..d907727c7b7a 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> @@ -1279,8 +1279,6 @@ static void mana_poll_tx_cq(struct mana_cq *cq)
> if (comp_read < 1)
> return;
>
> - apc->eth_stats.tx_cqes = comp_read;
> -
> for (i = 0; i < comp_read; i++) {
> struct mana_tx_comp_oob *cqe_oob;
>
> @@ -1363,8 +1361,6 @@ static void mana_poll_tx_cq(struct mana_cq *cq)
> WARN_ON_ONCE(1);
>
> cq->work_done = pkt_transmitted;
> -
> - apc->eth_stats.tx_cqes -= pkt_transmitted;
> }
>
> static void mana_post_pkt_rxq(struct mana_rxq *rxq)
> @@ -1626,15 +1622,11 @@ static void mana_poll_rx_cq(struct mana_cq *cq)
> {
> struct gdma_comp *comp = cq->gdma_comp_buf;
> struct mana_rxq *rxq = cq->rxq;
> - struct mana_port_context *apc;
> int comp_read, i;
>
> - apc = netdev_priv(rxq->ndev);
> -
> comp_read = mana_gd_poll_cq(cq->gdma_cq, comp, CQE_POLLING_BUFFER);
> WARN_ON_ONCE(comp_read > CQE_POLLING_BUFFER);
>
> - apc->eth_stats.rx_cqes = comp_read;
> rxq->xdp_flush = false;
>
> for (i = 0; i < comp_read; i++) {
> @@ -1646,8 +1638,6 @@ static void mana_poll_rx_cq(struct mana_cq *cq)
> return;
>
> mana_process_rx_cqe(rxq, cq, &comp[i]);
> -
> - apc->eth_stats.rx_cqes--;
> }
>
> if (rxq->xdp_flush)
> diff --git a/drivers/net/ethernet/microsoft/mana/mana_ethtool.c b/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
> index a64c81410dc1..0dc78679f620 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
> @@ -13,11 +13,9 @@ static const struct {
> } mana_eth_stats[] = {
> {"stop_queue", offsetof(struct mana_ethtool_stats, stop_queue)},
> {"wake_queue", offsetof(struct mana_ethtool_stats, wake_queue)},
> - {"tx_cqes", offsetof(struct mana_ethtool_stats, tx_cqes)},
> {"tx_cq_err", offsetof(struct mana_ethtool_stats, tx_cqe_err)},
> {"tx_cqe_unknown_type", offsetof(struct mana_ethtool_stats,
> tx_cqe_unknown_type)},
> - {"rx_cqes", offsetof(struct mana_ethtool_stats, rx_cqes)},
> {"rx_coalesced_err", offsetof(struct mana_ethtool_stats,
> rx_coalesced_err)},
> {"rx_cqe_unknown_type", offsetof(struct mana_ethtool_stats,
> diff --git a/include/net/mana/mana.h b/include/net/mana/mana.h
> index cd386aa7c7cc..9eef19972845 100644
> --- a/include/net/mana/mana.h
> +++ b/include/net/mana/mana.h
> @@ -347,10 +347,8 @@ struct mana_tx_qp {
> struct mana_ethtool_stats {
> u64 stop_queue;
> u64 wake_queue;
> - u64 tx_cqes;
> u64 tx_cqe_err;
> u64 tx_cqe_unknown_type;
> - u64 rx_cqes;
> u64 rx_coalesced_err;
> u64 rx_cqe_unknown_type;
> };
> --
> 2.25.1
>
>
--
/Horatiu
