Commit 1919b39f authored by Haiyang Zhang's avatar Haiyang Zhang Committed by Paolo Abeni
Browse files

net: mana: Fix perf regression: remove rx_cqes, tx_cqes counters 



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: bd7fc6e1 ("net: mana: Add new MANA VF performance counters for easier troubleshooting")
Signed-off-by: default avatarHaiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: default avatarHoratiu Vultur <horatiu.vultur@microchip.com>
Reviewed-by: default avatarJiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/1685115537-31675-1-git-send-email-haiyangz@microsoft.com


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 111d4674

drivers/net/ethernet/microsoft/mana/mana_en.c

+0 −10
Original line number Diff line number Diff line
@@ -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)

drivers/net/ethernet/microsoft/mana/mana_ethtool.c

+0 −2
Original line number Diff line number Diff line
@@ -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,

include/net/mana/mana.h

+0 −2
Original line number Diff line number Diff line
@@ -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;

};