net: mv643xx_eth: Limit the TSO segments and adjust stop/wake thresholds
Currently small MSS values may require too many TSO descriptors for
the default queue size. This commit prevents this situation by fixing
the maximum supported TSO number of segments to 100 and by setting a
minimum Tx queue size. The minimum Tx queue size is set so that at
least 2 worst-case skb can be accommodated.
In addition, the queue stop and wake thresholds values are adjusted
accordingly. The queue is stopped when there's room for only 1 worst-case
skb and waked when the number of descriptors is half that value.
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/marvell/mv643xx_eth.c b/drivers/net/ethernet/marvell/mv643xx_eth.c
index 97a60de..2cea86d 100644
--- a/drivers/net/ethernet/marvell/mv643xx_eth.c
+++ b/drivers/net/ethernet/marvell/mv643xx_eth.c
@@ -185,6 +185,10 @@
#define TSO_HEADER_SIZE 128
+/* Max number of allowed TCP segments for software TSO */
+#define MV643XX_MAX_TSO_SEGS 100
+#define MV643XX_MAX_SKB_DESCS (MV643XX_MAX_TSO_SEGS * 2 + MAX_SKB_FRAGS)
+
/*
* RX/TX descriptors.
*/
@@ -348,6 +352,9 @@
int tx_curr_desc;
int tx_used_desc;
+ int tx_stop_threshold;
+ int tx_wake_threshold;
+
char *tso_hdrs;
dma_addr_t tso_hdrs_dma;
@@ -497,7 +504,7 @@
if (netif_tx_queue_stopped(nq)) {
__netif_tx_lock(nq, smp_processor_id());
- if (txq->tx_ring_size - txq->tx_desc_count >= MAX_SKB_FRAGS + 1)
+ if (txq->tx_desc_count <= txq->tx_wake_threshold)
netif_tx_wake_queue(nq);
__netif_tx_unlock(nq);
}
@@ -897,7 +904,8 @@
}
}
-static int txq_submit_skb(struct tx_queue *txq, struct sk_buff *skb)
+static int txq_submit_skb(struct tx_queue *txq, struct sk_buff *skb,
+ struct net_device *dev)
{
struct mv643xx_eth_private *mp = txq_to_mp(txq);
int nr_frags = skb_shinfo(skb)->nr_frags;
@@ -910,11 +918,15 @@
cmd_sts = 0;
l4i_chk = 0;
- ret = skb_tx_csum(mp, skb, &l4i_chk, &cmd_sts, skb->len);
- if (ret) {
- dev_kfree_skb_any(skb);
- return ret;
+ if (txq->tx_ring_size - txq->tx_desc_count < MAX_SKB_FRAGS + 1) {
+ if (net_ratelimit())
+ netdev_err(dev, "tx queue full?!\n");
+ return -EBUSY;
}
+
+ ret = skb_tx_csum(mp, skb, &l4i_chk, &cmd_sts, skb->len);
+ if (ret)
+ return ret;
cmd_sts |= TX_FIRST_DESC | GEN_CRC | BUFFER_OWNED_BY_DMA;
tx_index = txq->tx_curr_desc++;
@@ -972,28 +984,17 @@
return NETDEV_TX_BUSY;
}
- if (txq->tx_ring_size - txq->tx_desc_count < MAX_SKB_FRAGS + 1) {
- if (net_ratelimit())
- netdev_err(dev, "tx queue full?!\n");
- txq->tx_dropped++;
- dev_kfree_skb_any(skb);
- return NETDEV_TX_OK;
- }
-
length = skb->len;
if (skb_is_gso(skb))
ret = txq_submit_tso(txq, skb, dev);
else
- ret = txq_submit_skb(txq, skb);
+ ret = txq_submit_skb(txq, skb, dev);
if (!ret) {
- int entries_left;
-
txq->tx_bytes += length;
txq->tx_packets++;
- entries_left = txq->tx_ring_size - txq->tx_desc_count;
- if (entries_left < MAX_SKB_FRAGS + 1)
+ if (txq->tx_desc_count >= txq->tx_stop_threshold)
netif_tx_stop_queue(nq);
} else if (ret == -EBUSY) {
return NETDEV_TX_BUSY;
@@ -1617,7 +1618,11 @@
return -EINVAL;
mp->rx_ring_size = er->rx_pending < 4096 ? er->rx_pending : 4096;
- mp->tx_ring_size = er->tx_pending < 4096 ? er->tx_pending : 4096;
+ mp->tx_ring_size = clamp_t(unsigned int, er->tx_pending,
+ MV643XX_MAX_SKB_DESCS * 2, 4096);
+ if (mp->tx_ring_size != er->tx_pending)
+ netdev_warn(dev, "TX queue size set to %u (requested %u)\n",
+ mp->tx_ring_size, er->tx_pending);
if (netif_running(dev)) {
mv643xx_eth_stop(dev);
@@ -1993,6 +1998,13 @@
txq->tx_ring_size = mp->tx_ring_size;
+ /* A queue must always have room for at least one skb.
+ * Therefore, stop the queue when the free entries reaches
+ * the maximum number of descriptors per skb.
+ */
+ txq->tx_stop_threshold = txq->tx_ring_size - MV643XX_MAX_SKB_DESCS;
+ txq->tx_wake_threshold = txq->tx_stop_threshold / 2;
+
txq->tx_desc_count = 0;
txq->tx_curr_desc = 0;
txq->tx_used_desc = 0;
@@ -2852,6 +2864,7 @@
struct mv643xx_eth_platform_data *pd)
{
struct net_device *dev = mp->dev;
+ unsigned int tx_ring_size;
if (is_valid_ether_addr(pd->mac_addr))
memcpy(dev->dev_addr, pd->mac_addr, ETH_ALEN);
@@ -2866,9 +2879,16 @@
mp->rxq_count = pd->rx_queue_count ? : 1;
- mp->tx_ring_size = DEFAULT_TX_QUEUE_SIZE;
+ tx_ring_size = DEFAULT_TX_QUEUE_SIZE;
if (pd->tx_queue_size)
- mp->tx_ring_size = pd->tx_queue_size;
+ tx_ring_size = pd->tx_queue_size;
+
+ mp->tx_ring_size = clamp_t(unsigned int, tx_ring_size,
+ MV643XX_MAX_SKB_DESCS * 2, 4096);
+ if (mp->tx_ring_size != tx_ring_size)
+ netdev_warn(dev, "TX queue size set to %u (requested %u)\n",
+ mp->tx_ring_size, tx_ring_size);
+
mp->tx_desc_sram_addr = pd->tx_sram_addr;
mp->tx_desc_sram_size = pd->tx_sram_size;
@@ -3095,6 +3115,7 @@
dev->hw_features = dev->features;
dev->priv_flags |= IFF_UNICAST_FLT;
+ dev->gso_max_segs = MV643XX_MAX_TSO_SEGS;
SET_NETDEV_DEV(dev, &pdev->dev);