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ibmvnic: Use ndo_get_stats64 to fix inaccurate SAR reporting

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VNIC testing on multi-core Power systems showed SAR stats drift
and packet rate inconsistencies under load.

Implements ndo_get_stats64 to provide safe aggregation of queue-level
atomic64 counters into rtnl_link_stats64 for use by tools like 'ip -s',
'ifconfig', and 'sar'. Switch to ndo_get_stats64 to align SAR reporting
with the standard kernel interface for retrieving netdev stats.

This removes redundant per-adapter stat updates, reduces overhead,
eliminates cacheline bouncing from hot path updates, and improves
the accuracy of reported packet rates.

Signed-off-by: Mingming Cao <mmc@linux.ibm.com>
Reviewed-by: Brian King <bjking1@linux.ibm.com>
Reviewed-by: Dave Marquardt <davemarq@linux.ibm.com>
Reviewed-by: Simon Horman <horms@kernel.org>

----
Changes since v3:
link to v3: https://www.spinics.net/lists/netdev/msg1107999.html
-- keep per queue counters as u64 (this patch) and drop off patch 1 in v3

Link: https://patch.msgid.link/20250716152115.61143-1-mmc@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Mingming Cao 2025-07-16 11:21:15 -04:00 committed by Jakub Kicinski
parent 0dce684793
commit efe28034ea
1 changed files with 20 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
drivers/net/ethernet/ibm/ibmvnic.c
View File

@ -2312,8 +2312,6 @@ static void ibmvnic_tx_scrq_clean_buffer(struct ibmvnic_adapter *adapter,
tx_pool->num_buffers - 1 :
tx_pool->consumer_index - 1;
tx_buff = &tx_pool->tx_buff[index];
adapter->netdev->stats.tx_packets--;
adapter->netdev->stats.tx_bytes -= tx_buff->skb->len;
adapter->tx_stats_buffers[queue_num].batched_packets--;
adapter->tx_stats_buffers[queue_num].bytes -=
tx_buff->skb->len;
@ -2647,9 +2645,6 @@ static netdev_tx_t ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev)
}
out:
rcu_read_unlock();
netdev->stats.tx_dropped += tx_dropped;
netdev->stats.tx_bytes += tx_bytes;
netdev->stats.tx_packets += tx_bpackets + tx_dpackets;
adapter->tx_send_failed += tx_send_failed;
adapter->tx_map_failed += tx_map_failed;
adapter->tx_stats_buffers[queue_num].batched_packets += tx_bpackets;
@ -3452,6 +3447,25 @@ static int ibmvnic_reset(struct ibmvnic_adapter *adapter,
return -ret;
}
static void ibmvnic_get_stats64(struct net_device *netdev,
struct rtnl_link_stats64 *stats)
{
struct ibmvnic_adapter *adapter = netdev_priv(netdev);
int i;
for (i = 0; i < adapter->req_rx_queues; i++) {
stats->rx_packets += adapter->rx_stats_buffers[i].packets;
stats->rx_bytes += adapter->rx_stats_buffers[i].bytes;
}
for (i = 0; i < adapter->req_tx_queues; i++) {
stats->tx_packets += adapter->tx_stats_buffers[i].batched_packets;
stats->tx_packets += adapter->tx_stats_buffers[i].direct_packets;
stats->tx_bytes += adapter->tx_stats_buffers[i].bytes;
stats->tx_dropped += adapter->tx_stats_buffers[i].dropped_packets;
}
}
static void ibmvnic_tx_timeout(struct net_device *dev, unsigned int txqueue)
{
struct ibmvnic_adapter *adapter = netdev_priv(dev);
@ -3567,8 +3581,6 @@ static int ibmvnic_poll(struct napi_struct *napi, int budget)
length = skb->len;
napi_gro_receive(napi, skb); /* send it up */
netdev->stats.rx_packets++;
netdev->stats.rx_bytes += length;
adapter->rx_stats_buffers[scrq_num].packets++;
adapter->rx_stats_buffers[scrq_num].bytes += length;
frames_processed++;
@ -3678,6 +3690,7 @@ static const struct net_device_ops ibmvnic_netdev_ops = {
.ndo_set_rx_mode = ibmvnic_set_multi,
.ndo_set_mac_address = ibmvnic_set_mac,
.ndo_validate_addr = eth_validate_addr,
.ndo_get_stats64 = ibmvnic_get_stats64,
.ndo_tx_timeout = ibmvnic_tx_timeout,
.ndo_change_mtu = ibmvnic_change_mtu,
.ndo_features_check = ibmvnic_features_check,