USBNET: increase max rx/tx qlen for improving USB3 thoughtput

The default RX_QLEN()/TX_QLEN() didn't consider super speed
USB device, so only max 4 URBs are scheduled at the same time
for tx/rx, then USB3 NIC can't perform very well.

With this patch, both rx and tx thoughput are increased more than
100Mbps when doing iperf test on ax88179_178a USB 3.0 NIC.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index d74de074a438bc285a47e4d8b2cb807bf9c05453..e4811d7b5af1cb19aad389f231781cede61c3f81 100644 (file)
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -355,6 +355,15 @@ void usbnet_update_max_qlen(struct usbnet *dev)
                dev->rx_qlen = MAX_QUEUE_MEMORY / dev->rx_urb_size;
                dev->tx_qlen = MAX_QUEUE_MEMORY / dev->hard_mtu;
                break;
+       case USB_SPEED_SUPER:
+               /*
+                * Not take default 5ms qlen for super speed HC to
+                * save memory, and iperf tests show 2.5ms qlen can
+                * work well
+                */
+               dev->rx_qlen = 5 * MAX_QUEUE_MEMORY / dev->rx_urb_size;
+               dev->tx_qlen = 5 * MAX_QUEUE_MEMORY / dev->hard_mtu;
+               break;
        default:
                dev->rx_qlen = dev->tx_qlen = 4;
        }