pcnet32: Fix PCnet32 performance bug on non-coherent architecutres
authorDon Fry <pcnet32@verizon.net>
Tue, 6 Mar 2007 02:13:09 +0000 (18:13 -0800)
committerJeff Garzik <jeff@garzik.org>
Tue, 6 Mar 2007 11:14:54 +0000 (06:14 -0500)
The PCnet32 driver always passed the the size of the largest possible packet
to the pci_dma_sync_single_for_cpu and pci_dma_sync_single_for_device.
This results in a fairly large "colateral damage" in the caches and makes
the flush operation itself much slower.  On a system with a 40MHz CPU this
patch increases network bandwidth by about 12%.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Don Fry <pcnet32@verizon.net>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
drivers/net/pcnet32.c

index 36f9d988278f76771292c45a365a41ddd4ad478e..4d94ba7899bfaf181ea972cb670b0555b575d38a 100644 (file)
@@ -1234,14 +1234,14 @@ static void pcnet32_rx_entry(struct net_device *dev,
                skb_put(skb, pkt_len);  /* Make room */
                pci_dma_sync_single_for_cpu(lp->pci_dev,
                                            lp->rx_dma_addr[entry],
-                                           PKT_BUF_SZ - 2,
+                                           pkt_len,
                                            PCI_DMA_FROMDEVICE);
                eth_copy_and_sum(skb,
                                 (unsigned char *)(lp->rx_skbuff[entry]->data),
                                 pkt_len, 0);
                pci_dma_sync_single_for_device(lp->pci_dev,
                                               lp->rx_dma_addr[entry],
-                                              PKT_BUF_SZ - 2,
+                                              pkt_len,
                                               PCI_DMA_FROMDEVICE);
        }
        lp->stats.rx_bytes += skb->len;