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.

For example, a workload is iperf with 128 threads, and with RPS enabled. We saw perf regression of 25% with the previous patch adding the counters. And this patch eliminates the regression.

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.

Cc: stable@vger.kernel.org Fixes: bd7fc6e1957c ("net: mana: Add new MANA VF performance counters for easier troubleshooting") Signed-off-by: Haiyang Zhang haiyangz@microsoft.com Reviewed-by: Horatiu Vultur horatiu.vultur@microchip.com Reviewed-by: Jiri Pirko jiri@nvidia.com

--- V3: Add test example as suggested by Jakub Kicinski. V2: Same as V1, except adding more Cc's. --- 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; };