pasemi_mac: performance tweaks

pasemi_mac: performance tweaks

* Seems like we do better with a smaller RX ring, probably because chances of
  still having the SKB cached are better
* Const-ify variables to get better code generation and fewer reloads
* Move prefetching around a little, and try to prefetch the whole SKB
* Set NETIF_F_HIGHDMA
* Misc other minor tweaks

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 68 insertions, 46 deletions

diff --git a/drivers/net/pasemi_mac.c b/drivers/net/pasemi_mac.c
index a50eb34ece5d..c6e24a8dcf72 100644
--- a/drivers/net/pasemi_mac.c
+++ b/drivers/net/pasemi_mac.c
@@ -56,7 +56,7 @@
 
 
 /* Must be a power of two */
-#define RX_RING_SIZE 4096
+#define RX_RING_SIZE 1024
 #define TX_RING_SIZE 4096
 
 #define DEFAULT_MSG_ENABLE        \
@@ -103,12 +103,12 @@ static void write_iob_reg(unsigned int reg, unsigned int val)
         pasemi_write_iob_reg(reg, val);
 }
 
-static unsigned int read_mac_reg(struct pasemi_mac *mac, unsigned int reg)
+static unsigned int read_mac_reg(const struct pasemi_mac *mac, unsigned int reg)
 {
         return pasemi_read_mac_reg(mac->dma_if, reg);
 }
 
-static void write_mac_reg(struct pasemi_mac *mac, unsigned int reg,
+static void write_mac_reg(const struct pasemi_mac *mac, unsigned int reg,
                           unsigned int val)
 {
         pasemi_write_mac_reg(mac->dma_if, reg, val);
@@ -124,16 +124,26 @@ static void write_dma_reg(unsigned int reg, unsigned int val)
         pasemi_write_dma_reg(reg, val);
 }
 
-static struct pasemi_mac_rxring *rx_ring(struct pasemi_mac *mac)
+static struct pasemi_mac_rxring *rx_ring(const struct pasemi_mac *mac)
 {
         return mac->rx;
 }
 
-static struct pasemi_mac_txring *tx_ring(struct pasemi_mac *mac)
+static struct pasemi_mac_txring *tx_ring(const struct pasemi_mac *mac)
 {
         return mac->tx;
 }
 
+static inline void prefetch_skb(const struct sk_buff *skb)
+{
+        const void *d = skb;
+
+        prefetch(d);
+        prefetch(d+64);
+        prefetch(d+128);
+        prefetch(d+192);
+}
+
 static int mac_to_intf(struct pasemi_mac *mac)
 {
         struct pci_dev *pdev = mac->pdev;
@@ -211,19 +221,18 @@ static int pasemi_get_mac_addr(struct pasemi_mac *mac)
 
 static int pasemi_mac_unmap_tx_skb(struct pasemi_mac *mac,
                                     struct sk_buff *skb,
-                                    dma_addr_t *dmas)
+                                    const dma_addr_t *dmas)
 {
         int f;
         int nfrags = skb_shinfo(skb)->nr_frags;
+        struct pci_dev *pdev = mac->dma_pdev;
 
-        pci_unmap_single(mac->dma_pdev, dmas[0], skb_headlen(skb),
-                         PCI_DMA_TODEVICE);
+        pci_unmap_single(pdev, dmas[0], skb_headlen(skb), PCI_DMA_TODEVICE);
 
         for (f = 0; f < nfrags; f++) {
                 skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
 
-                pci_unmap_page(mac->dma_pdev, dmas[f+1], frag->size,
-                               PCI_DMA_TODEVICE);
+                pci_unmap_page(pdev, dmas[f+1], frag->size, PCI_DMA_TODEVICE);
         }
         dev_kfree_skb_irq(skb);
 
@@ -233,7 +242,7 @@ static int pasemi_mac_unmap_tx_skb(struct pasemi_mac *mac,
         return (nfrags + 3) & ~1;
 }
 
-static int pasemi_mac_setup_rx_resources(struct net_device *dev)
+static int pasemi_mac_setup_rx_resources(const struct net_device *dev)
 {
         struct pasemi_mac_rxring *ring;
         struct pasemi_mac *mac = netdev_priv(dev);
@@ -277,7 +286,7 @@ static int pasemi_mac_setup_rx_resources(struct net_device *dev)
                       PAS_DMA_RXCHAN_BASEU_BRBH(ring->chan.ring_dma >> 32) |
                       PAS_DMA_RXCHAN_BASEU_SIZ(RX_RING_SIZE >> 3));
 
-        cfg = PAS_DMA_RXCHAN_CFG_HBU(1);
+        cfg = PAS_DMA_RXCHAN_CFG_HBU(2);
 
         if (translation_enabled())
                 cfg |= PAS_DMA_RXCHAN_CFG_CTR;
@@ -291,7 +300,7 @@ static int pasemi_mac_setup_rx_resources(struct net_device *dev)
                       PAS_DMA_RXINT_BASEU_BRBH(ring->buf_dma >> 32) |
                       PAS_DMA_RXINT_BASEU_SIZ(RX_RING_SIZE >> 3));
 
-        cfg = PAS_DMA_RXINT_CFG_DHL(1) | PAS_DMA_RXINT_CFG_L2 |
+        cfg = PAS_DMA_RXINT_CFG_DHL(2) | PAS_DMA_RXINT_CFG_L2 |
               PAS_DMA_RXINT_CFG_LW | PAS_DMA_RXINT_CFG_RBP |
               PAS_DMA_RXINT_CFG_HEN;
 
@@ -316,7 +325,7 @@ out_chan:
 }
 
 static struct pasemi_mac_txring *
-pasemi_mac_setup_tx_resources(struct net_device *dev)
+pasemi_mac_setup_tx_resources(const struct net_device *dev)
 {
         struct pasemi_mac *mac = netdev_priv(dev);
         u32 val;
@@ -439,9 +448,10 @@ static void pasemi_mac_free_rx_resources(struct pasemi_mac *mac)
         mac->rx = NULL;
 }
 
-static void pasemi_mac_replenish_rx_ring(struct net_device *dev, int limit)
+static void pasemi_mac_replenish_rx_ring(const struct net_device *dev,
+                                         const int limit)
 {
-        struct pasemi_mac *mac = netdev_priv(dev);
+        const struct pasemi_mac *mac = netdev_priv(dev);
         struct pasemi_mac_rxring *rx = rx_ring(mac);
         int fill, count;
 
@@ -492,7 +502,7 @@ static void pasemi_mac_replenish_rx_ring(struct net_device *dev, int limit)
                                 (RX_RING_SIZE - 1);
 }
 
-static void pasemi_mac_restart_rx_intr(struct pasemi_mac *mac)
+static void pasemi_mac_restart_rx_intr(const struct pasemi_mac *mac)
 {
         unsigned int reg, pcnt;
         /* Re-enable packet count interrupts: finally
@@ -506,7 +516,7 @@ static void pasemi_mac_restart_rx_intr(struct pasemi_mac *mac)
         write_iob_reg(PAS_IOB_DMA_RXCH_RESET(mac->rx->chan.chno), reg);
 }
 
-static void pasemi_mac_restart_tx_intr(struct pasemi_mac *mac)
+static void pasemi_mac_restart_tx_intr(const struct pasemi_mac *mac)
 {
         unsigned int reg, pcnt;
 
@@ -519,7 +529,8 @@ static void pasemi_mac_restart_tx_intr(struct pasemi_mac *mac)
 }
 
 
-static inline void pasemi_mac_rx_error(struct pasemi_mac *mac, u64 macrx)
+static inline void pasemi_mac_rx_error(const struct pasemi_mac *mac,
+                                       const u64 macrx)
 {
         unsigned int rcmdsta, ccmdsta;
         struct pasemi_dmachan *chan = &rx_ring(mac)->chan;
@@ -537,7 +548,8 @@ static inline void pasemi_mac_rx_error(struct pasemi_mac *mac, u64 macrx)
                 rcmdsta, ccmdsta);
 }
 
-static inline void pasemi_mac_tx_error(struct pasemi_mac *mac, u64 mactx)
+static inline void pasemi_mac_tx_error(const struct pasemi_mac *mac,
+                                       const u64 mactx)
 {
         unsigned int cmdsta;
         struct pasemi_dmachan *chan = &tx_ring(mac)->chan;
@@ -553,19 +565,22 @@ static inline void pasemi_mac_tx_error(struct pasemi_mac *mac, u64 mactx)
         printk(KERN_ERR "pasemi_mac: tcmdsta 0x%08x\n", cmdsta);
 }
 
-static int pasemi_mac_clean_rx(struct pasemi_mac_rxring *rx, int limit)
+static int pasemi_mac_clean_rx(struct pasemi_mac_rxring *rx,
+                               const int limit)
 {
-        struct pasemi_dmachan *chan = &rx->chan;
+        const struct pasemi_dmachan *chan = &rx->chan;
         struct pasemi_mac *mac = rx->mac;
+        struct pci_dev *pdev = mac->dma_pdev;
         unsigned int n;
-        int count;
+        int count, buf_index, tot_bytes, packets;
         struct pasemi_mac_buffer *info;
         struct sk_buff *skb;
         unsigned int len;
-        u64 macrx;
+        u64 macrx, eval;
         dma_addr_t dma;
-        int buf_index;
-        u64 eval;
+
+        tot_bytes = 0;
+        packets = 0;
 
         spin_lock(&rx->lock);
 
@@ -575,6 +590,7 @@ static int pasemi_mac_clean_rx(struct pasemi_mac_rxring *rx, int limit)
 
         for (count = 0; count < limit; count++) {
                 macrx = RX_DESC(rx, n);
+                prefetch(&RX_DESC(rx, n+4));
 
                 if ((macrx & XCT_MACRX_E) ||
                     (*chan->status & PAS_STATUS_ERROR))
@@ -596,12 +612,12 @@ static int pasemi_mac_clean_rx(struct pasemi_mac_rxring *rx, int limit)
 
                 skb = info->skb;
 
-                prefetch(skb);
-                prefetch(&skb->data_len);
+                prefetch_skb(skb);
 
                 len = (macrx & XCT_MACRX_LLEN_M) >> XCT_MACRX_LLEN_S;
 
-                pci_unmap_single(mac->dma_pdev, dma, len, PCI_DMA_FROMDEVICE);
+                pci_unmap_single(pdev, dma, BUF_SIZE-LOCAL_SKB_ALIGN,
+                                 PCI_DMA_FROMDEVICE);
 
                 if (macrx & XCT_MACRX_CRC) {
                         /* CRC error flagged */
@@ -628,9 +644,6 @@ static int pasemi_mac_clean_rx(struct pasemi_mac_rxring *rx, int limit)
 
                 info->dma = 0;
 
-                /* Don't include CRC */
-                skb_put(skb, len-4);
-
                 if (likely((macrx & XCT_MACRX_HTY_M) == XCT_MACRX_HTY_IPV4_OK)) {
                         skb->ip_summed = CHECKSUM_UNNECESSARY;
                         skb->csum = (macrx & XCT_MACRX_CSUM_M) >>
@@ -638,8 +651,11 @@ static int pasemi_mac_clean_rx(struct pasemi_mac_rxring *rx, int limit)
                 } else
                         skb->ip_summed = CHECKSUM_NONE;
 
-                mac->netdev->stats.rx_bytes += len;
-                mac->netdev->stats.rx_packets++;
+                packets++;
+                tot_bytes += len;
+
+                /* Don't include CRC */
+                skb_put(skb, len-4);
 
                 skb->protocol = eth_type_trans(skb, mac->netdev);
                 netif_receive_skb(skb);
@@ -672,6 +688,9 @@ next:
 
         pasemi_mac_replenish_rx_ring(mac->netdev, count);
 
+        mac->netdev->stats.rx_bytes += tot_bytes;
+        mac->netdev->stats.rx_packets += packets;
+
         spin_unlock(&rx_ring(mac)->lock);
 
         return count;
@@ -758,10 +777,10 @@ restart:
 
 static irqreturn_t pasemi_mac_rx_intr(int irq, void *data)
 {
-        struct pasemi_mac_rxring *rxring = data;
+        const struct pasemi_mac_rxring *rxring = data;
         struct pasemi_mac *mac = rxring->mac;
         struct net_device *dev = mac->netdev;
-        struct pasemi_dmachan *chan = &rxring->chan;
+        const struct pasemi_dmachan *chan = &rxring->chan;
         unsigned int reg;
 
         if (!(*chan->status & PAS_STATUS_CAUSE_M))
@@ -789,7 +808,7 @@ static irqreturn_t pasemi_mac_rx_intr(int irq, void *data)
 static irqreturn_t pasemi_mac_tx_intr(int irq, void *data)
 {
         struct pasemi_mac_txring *txring = data;
-        struct pasemi_dmachan *chan = &txring->chan;
+        const struct pasemi_dmachan *chan = &txring->chan;
         unsigned int reg, pcnt;
 
         if (!(*chan->status & PAS_STATUS_CAUSE_M))
@@ -1158,6 +1177,7 @@ static int pasemi_mac_start_tx(struct sk_buff *skb, struct net_device *dev)
         unsigned int map_size[MAX_SKB_FRAGS+1];
         unsigned long flags;
         int i, nfrags;
+        int fill;
 
         dflags = XCT_MACTX_O | XCT_MACTX_ST | XCT_MACTX_CRC_PAD;
 
@@ -1205,6 +1225,8 @@ static int pasemi_mac_start_tx(struct sk_buff *skb, struct net_device *dev)
 
         spin_lock_irqsave(&txring->lock, flags);
 
+        fill = txring->next_to_fill;
+
         /* Avoid stepping on the same cache line that the DMA controller
          * is currently about to send, so leave at least 8 words available.
          * Total free space needed is mactx + fragments + 8
@@ -1215,13 +1237,13 @@ static int pasemi_mac_start_tx(struct sk_buff *skb, struct net_device *dev)
                 goto out_err;
         }
 
-        TX_DESC(txring, txring->next_to_fill) = mactx;
-        txring->next_to_fill++;
-        TX_DESC_INFO(txring, txring->next_to_fill).skb = skb;
+        TX_DESC(txring, fill) = mactx;
+        fill++;
+        TX_DESC_INFO(txring, fill).skb = skb;
         for (i = 0; i <= nfrags; i++) {
-                TX_DESC(txring, txring->next_to_fill+i) =
+                TX_DESC(txring, fill+i) =
                         XCT_PTR_LEN(map_size[i]) | XCT_PTR_ADDR(map[i]);
-                TX_DESC_INFO(txring, txring->next_to_fill+i).dma = map[i];
+                TX_DESC_INFO(txring, fill+i).dma = map[i];
         }
 
         /* We have to add an even number of 8-byte entries to the ring
@@ -1231,8 +1253,7 @@ static int pasemi_mac_start_tx(struct sk_buff *skb, struct net_device *dev)
         if (nfrags & 1)
                 nfrags++;
 
-        txring->next_to_fill = (txring->next_to_fill + nfrags + 1) &
-                                (TX_RING_SIZE-1);
+        txring->next_to_fill = (fill + nfrags + 1) & (TX_RING_SIZE-1);
 
         dev->stats.tx_packets++;
         dev->stats.tx_bytes += skb->len;
@@ -1255,7 +1276,7 @@ out_err_nolock:
 
 static void pasemi_mac_set_rx_mode(struct net_device *dev)
 {
-        struct pasemi_mac *mac = netdev_priv(dev);
+        const struct pasemi_mac *mac = netdev_priv(dev);
         unsigned int flags;
 
         flags = read_mac_reg(mac, PAS_MAC_CFG_PCFG);
@@ -1317,7 +1338,8 @@ pasemi_mac_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
         netif_napi_add(dev, &mac->napi, pasemi_mac_poll, 64);
 
-        dev->features = NETIF_F_IP_CSUM | NETIF_F_LLTX | NETIF_F_SG;
+        dev->features = NETIF_F_IP_CSUM | NETIF_F_LLTX | NETIF_F_SG |
+                        NETIF_F_HIGHDMA;
 
         mac->dma_pdev = pci_get_device(PCI_VENDOR_ID_PASEMI, 0xa007, NULL);
         if (!mac->dma_pdev) {