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net: mvpp2: limit TSO segments and use stop/wake thresholds

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Too many TSO descriptors can be required for the default queue size,
when using small MSS values for example. Prevent this by adding a
maximum number of allowed TSO segments (300). In addition set a stop and
a wake thresholds to stop the queue when there's no room for a 1 "worst
case scenario skb". Wake up the queue when the number of descriptors is
low enough.

Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Antoine Tenart 2017-10-30 11:23:31 +01:00 committed by David S. Miller
parent 1d7d15d79f
commit 1d17db08c0
1 changed files with 16 additions and 2 deletions
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18
drivers/net/ethernet/marvell/mvpp2.c
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@ -493,6 +493,13 @@
/* Maximum number of TXQs used by single port */
#define MVPP2_MAX_TXQ 8
/* MVPP2_MAX_TSO_SEGS is the maximum number of fragments to allow in the GSO
* skb. As we need a maxium of two descriptors per fragments (1 header, 1 data),
* multiply this value by two to count the maximum number of skb descs needed.
*/
#define MVPP2_MAX_TSO_SEGS 300
#define MVPP2_MAX_SKB_DESCS (MVPP2_MAX_TSO_SEGS * 2 + MAX_SKB_FRAGS)
/* Dfault number of RXQs in use */
#define MVPP2_DEFAULT_RXQ 4
@ -1045,6 +1052,9 @@ struct mvpp2_txq_pcpu {
*/
int count;
int wake_threshold;
int stop_threshold;
/* Number of Tx DMA descriptors reserved for each CPU */
int reserved_num;
@ -5393,7 +5403,7 @@ static void mvpp2_txq_done(struct mvpp2_port *port, struct mvpp2_tx_queue *txq,
txq_pcpu->count -= tx_done;
if (netif_tx_queue_stopped(nq))
if (txq_pcpu->size - txq_pcpu->count >= MAX_SKB_FRAGS + 1)
if (txq_pcpu->count <= txq_pcpu->wake_threshold)
netif_tx_wake_queue(nq);
}
@ -5636,6 +5646,9 @@ static int mvpp2_txq_init(struct mvpp2_port *port,
txq_pcpu->txq_put_index = 0;
txq_pcpu->txq_get_index = 0;
txq_pcpu->stop_threshold = txq->size - MVPP2_MAX_SKB_DESCS;
txq_pcpu->wake_threshold = txq_pcpu->stop_threshold / 2;
txq_pcpu->tso_headers =
dma_alloc_coherent(port->dev->dev.parent,
txq_pcpu->size * TSO_HEADER_SIZE,
@ -6508,7 +6521,7 @@ static int mvpp2_tx(struct sk_buff *skb, struct net_device *dev)
wmb();
mvpp2_aggr_txq_pend_desc_add(port, frags);
if (txq_pcpu->size - txq_pcpu->count < MAX_SKB_FRAGS + 1)
if (txq_pcpu->count >= txq_pcpu->stop_threshold)
netif_tx_stop_queue(nq);
u64_stats_update_begin(&stats->syncp);
@ -7732,6 +7745,7 @@ static int mvpp2_port_probe(struct platform_device *pdev,
dev->features = features | NETIF_F_RXCSUM;
dev->hw_features |= features | NETIF_F_RXCSUM | NETIF_F_GRO;
dev->vlan_features |= features;
dev->gso_max_segs = MVPP2_MAX_TSO_SEGS;
/* MTU range: 68 - 9676 */
dev->min_mtu = ETH_MIN_MTU;