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net: mvpp2: software tso support
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The patch uses the tso API to implement the tso functionality in Marvell
PPv2 driver.

Using iperf and 10G ports, using TSO shows a significant performance
improvement by a factor 2 to reach around 9.5Gbps in TX; as well as a
significant CPU usage drop (from 25% to 15%).

Signed-off-by: Antoine Tenart <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@atenart @davem330
atenart authored and davem330 committed Aug 24, 2017
1 parent 85affd7 commit 186cd4d
Showing 1 changed file with 157 additions and 14 deletions.
171 changes: 157 additions & 14 deletions drivers/net/ethernet/marvell/mvpp2.c
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@
#include <uapi/linux/ppp_defs.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/tso.h>

/* RX Fifo Registers */
#define MVPP2_RX_DATA_FIFO_SIZE_REG(port) (0x00 + 4 * (port))
Expand Down Expand Up @@ -1010,6 +1011,10 @@ struct mvpp2_txq_pcpu {

/* Index of the TX DMA descriptor to be cleaned up */
int txq_get_index;

/* DMA buffer for TSO headers */
char *tso_headers;
dma_addr_t tso_headers_dma;
};

struct mvpp2_tx_queue {
Expand Down Expand Up @@ -5494,13 +5499,26 @@ static int mvpp2_txq_init(struct mvpp2_port *port,
txq_pcpu->reserved_num = 0;
txq_pcpu->txq_put_index = 0;
txq_pcpu->txq_get_index = 0;

txq_pcpu->tso_headers =
dma_alloc_coherent(port->dev->dev.parent,
MVPP2_AGGR_TXQ_SIZE * TSO_HEADER_SIZE,
&txq_pcpu->tso_headers_dma,
GFP_KERNEL);
if (!txq_pcpu->tso_headers)
goto cleanup;
}

return 0;
cleanup:
for_each_present_cpu(cpu) {
txq_pcpu = per_cpu_ptr(txq->pcpu, cpu);
kfree(txq_pcpu->buffs);

dma_free_coherent(port->dev->dev.parent,
MVPP2_AGGR_TXQ_SIZE * MVPP2_DESC_ALIGNED_SIZE,
txq_pcpu->tso_headers,
txq_pcpu->tso_headers_dma);
}

dma_free_coherent(port->dev->dev.parent,
Expand All @@ -5520,6 +5538,11 @@ static void mvpp2_txq_deinit(struct mvpp2_port *port,
for_each_present_cpu(cpu) {
txq_pcpu = per_cpu_ptr(txq->pcpu, cpu);
kfree(txq_pcpu->buffs);

dma_free_coherent(port->dev->dev.parent,
MVPP2_AGGR_TXQ_SIZE * MVPP2_DESC_ALIGNED_SIZE,
txq_pcpu->tso_headers,
txq_pcpu->tso_headers_dma);
}

if (txq->descs)
Expand Down Expand Up @@ -6049,6 +6072,123 @@ static int mvpp2_tx_frag_process(struct mvpp2_port *port, struct sk_buff *skb,
return -ENOMEM;
}

static inline void mvpp2_tso_put_hdr(struct sk_buff *skb,
struct net_device *dev,
struct mvpp2_tx_queue *txq,
struct mvpp2_tx_queue *aggr_txq,
struct mvpp2_txq_pcpu *txq_pcpu,
int hdr_sz)
{
struct mvpp2_port *port = netdev_priv(dev);
struct mvpp2_tx_desc *tx_desc = mvpp2_txq_next_desc_get(aggr_txq);
dma_addr_t addr;

mvpp2_txdesc_txq_set(port, tx_desc, txq->id);
mvpp2_txdesc_size_set(port, tx_desc, hdr_sz);

addr = txq_pcpu->tso_headers_dma +
txq_pcpu->txq_put_index * TSO_HEADER_SIZE;
mvpp2_txdesc_offset_set(port, tx_desc, addr & MVPP2_TX_DESC_ALIGN);
mvpp2_txdesc_dma_addr_set(port, tx_desc, addr & ~MVPP2_TX_DESC_ALIGN);

mvpp2_txdesc_cmd_set(port, tx_desc, mvpp2_skb_tx_csum(port, skb) |
MVPP2_TXD_F_DESC |
MVPP2_TXD_PADDING_DISABLE);
mvpp2_txq_inc_put(port, txq_pcpu, NULL, tx_desc);
}

static inline int mvpp2_tso_put_data(struct sk_buff *skb,
struct net_device *dev, struct tso_t *tso,
struct mvpp2_tx_queue *txq,
struct mvpp2_tx_queue *aggr_txq,
struct mvpp2_txq_pcpu *txq_pcpu,
int sz, bool left, bool last)
{
struct mvpp2_port *port = netdev_priv(dev);
struct mvpp2_tx_desc *tx_desc = mvpp2_txq_next_desc_get(aggr_txq);
dma_addr_t buf_dma_addr;

mvpp2_txdesc_txq_set(port, tx_desc, txq->id);
mvpp2_txdesc_size_set(port, tx_desc, sz);

buf_dma_addr = dma_map_single(dev->dev.parent, tso->data, sz,
DMA_TO_DEVICE);
if (unlikely(dma_mapping_error(dev->dev.parent, buf_dma_addr))) {
mvpp2_txq_desc_put(txq);
return -ENOMEM;
}

mvpp2_txdesc_offset_set(port, tx_desc,
buf_dma_addr & MVPP2_TX_DESC_ALIGN);
mvpp2_txdesc_dma_addr_set(port, tx_desc,
buf_dma_addr & ~MVPP2_TX_DESC_ALIGN);

if (!left) {
mvpp2_txdesc_cmd_set(port, tx_desc, MVPP2_TXD_L_DESC);
if (last) {
mvpp2_txq_inc_put(port, txq_pcpu, skb, tx_desc);
return 0;
}
} else {
mvpp2_txdesc_cmd_set(port, tx_desc, 0);
}

mvpp2_txq_inc_put(port, txq_pcpu, NULL, tx_desc);
return 0;
}

static int mvpp2_tx_tso(struct sk_buff *skb, struct net_device *dev,
struct mvpp2_tx_queue *txq,
struct mvpp2_tx_queue *aggr_txq,
struct mvpp2_txq_pcpu *txq_pcpu)
{
struct mvpp2_port *port = netdev_priv(dev);
struct tso_t tso;
int hdr_sz = skb_transport_offset(skb) + tcp_hdrlen(skb);
int i, len, descs = 0;

/* Check number of available descriptors */
if (mvpp2_aggr_desc_num_check(port->priv, aggr_txq,
tso_count_descs(skb)) ||
mvpp2_txq_reserved_desc_num_proc(port->priv, txq, txq_pcpu,
tso_count_descs(skb)))
return 0;

tso_start(skb, &tso);
len = skb->len - hdr_sz;
while (len > 0) {
int left = min_t(int, skb_shinfo(skb)->gso_size, len);
char *hdr = txq_pcpu->tso_headers +
txq_pcpu->txq_put_index * TSO_HEADER_SIZE;

len -= left;
descs++;

tso_build_hdr(skb, hdr, &tso, left, len == 0);
mvpp2_tso_put_hdr(skb, dev, txq, aggr_txq, txq_pcpu, hdr_sz);

while (left > 0) {
int sz = min_t(int, tso.size, left);
left -= sz;
descs++;

if (mvpp2_tso_put_data(skb, dev, &tso, txq, aggr_txq,
txq_pcpu, sz, left, len == 0))
goto release;
tso_build_data(skb, &tso, sz);
}
}

return descs;

release:
for (i = descs - 1; i >= 0; i--) {
struct mvpp2_tx_desc *tx_desc = txq->descs + i;
tx_desc_unmap_put(port, txq, tx_desc);
}
return 0;
}

/* Main tx processing */
static int mvpp2_tx(struct sk_buff *skb, struct net_device *dev)
{
Expand All @@ -6066,6 +6206,10 @@ static int mvpp2_tx(struct sk_buff *skb, struct net_device *dev)
txq_pcpu = this_cpu_ptr(txq->pcpu);
aggr_txq = &port->priv->aggr_txqs[smp_processor_id()];

if (skb_is_gso(skb)) {
frags = mvpp2_tx_tso(skb, dev, txq, aggr_txq, txq_pcpu);
goto out;
}
frags = skb_shinfo(skb)->nr_frags + 1;

/* Check number of available descriptors */
Expand Down Expand Up @@ -6115,22 +6259,21 @@ static int mvpp2_tx(struct sk_buff *skb, struct net_device *dev)
}
}

txq_pcpu->reserved_num -= frags;
txq_pcpu->count += frags;
aggr_txq->count += frags;

/* Enable transmit */
wmb();
mvpp2_aggr_txq_pend_desc_add(port, frags);

if (txq_pcpu->size - txq_pcpu->count < MAX_SKB_FRAGS + 1) {
struct netdev_queue *nq = netdev_get_tx_queue(dev, txq_id);

netif_tx_stop_queue(nq);
}
out:
if (frags > 0) {
struct mvpp2_pcpu_stats *stats = this_cpu_ptr(port->stats);
struct netdev_queue *nq = netdev_get_tx_queue(dev, txq_id);

txq_pcpu->reserved_num -= frags;
txq_pcpu->count += frags;
aggr_txq->count += frags;

/* Enable transmit */
wmb();
mvpp2_aggr_txq_pend_desc_add(port, frags);

if (txq_pcpu->size - txq_pcpu->count < MAX_SKB_FRAGS + 1)
netif_tx_stop_queue(nq);

u64_stats_update_begin(&stats->syncp);
stats->tx_packets++;
Expand Down Expand Up @@ -7255,7 +7398,7 @@ static int mvpp2_port_probe(struct platform_device *pdev,
}
}

features = NETIF_F_SG | NETIF_F_IP_CSUM;
features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO;
dev->features = features | NETIF_F_RXCSUM;
dev->hw_features |= features | NETIF_F_RXCSUM | NETIF_F_GRO;
dev->vlan_features |= features;
Expand Down

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