[PATCH 5.3 089/140] net: hisilicon: Fix ping latency when deal with high throughput

From: Greg Kroah-Hartman
Date: Fri Nov 08 2019 - 14:08:30 EST


From: Jiangfeng Xiao <xiaojiangfeng@xxxxxxxxxx>

[ Upstream commit e56bd641ca61beb92b135298d5046905f920b734 ]

This is due to error in over budget processing.
When dealing with high throughput, the used buffers
that exceeds the budget is not cleaned up. In addition,
it takes a lot of cycles to clean up the used buffer,
and then the buffer where the valid data is located can take effect.

Signed-off-by: Jiangfeng Xiao <xiaojiangfeng@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/ethernet/hisilicon/hip04_eth.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

--- a/drivers/net/ethernet/hisilicon/hip04_eth.c
+++ b/drivers/net/ethernet/hisilicon/hip04_eth.c
@@ -237,6 +237,7 @@ struct hip04_priv {
dma_addr_t rx_phys[RX_DESC_NUM];
unsigned int rx_head;
unsigned int rx_buf_size;
+ unsigned int rx_cnt_remaining;

struct device_node *phy_node;
struct phy_device *phy;
@@ -575,7 +576,6 @@ static int hip04_rx_poll(struct napi_str
struct hip04_priv *priv = container_of(napi, struct hip04_priv, napi);
struct net_device *ndev = priv->ndev;
struct net_device_stats *stats = &ndev->stats;
- unsigned int cnt = hip04_recv_cnt(priv);
struct rx_desc *desc;
struct sk_buff *skb;
unsigned char *buf;
@@ -588,8 +588,8 @@ static int hip04_rx_poll(struct napi_str

/* clean up tx descriptors */
tx_remaining = hip04_tx_reclaim(ndev, false);
-
- while (cnt && !last) {
+ priv->rx_cnt_remaining += hip04_recv_cnt(priv);
+ while (priv->rx_cnt_remaining && !last) {
buf = priv->rx_buf[priv->rx_head];
skb = build_skb(buf, priv->rx_buf_size);
if (unlikely(!skb)) {
@@ -635,11 +635,13 @@ refill:
hip04_set_recv_desc(priv, phys);

priv->rx_head = RX_NEXT(priv->rx_head);
- if (rx >= budget)
+ if (rx >= budget) {
+ --priv->rx_cnt_remaining;
goto done;
+ }

- if (--cnt == 0)
- cnt = hip04_recv_cnt(priv);
+ if (--priv->rx_cnt_remaining == 0)
+ priv->rx_cnt_remaining += hip04_recv_cnt(priv);
}

if (!(priv->reg_inten & RCV_INT)) {
@@ -724,6 +726,7 @@ static int hip04_mac_open(struct net_dev
int i;

priv->rx_head = 0;
+ priv->rx_cnt_remaining = 0;
priv->tx_head = 0;
priv->tx_tail = 0;
hip04_reset_ppe(priv);