[IrDA]: irda-usb TX path optimization (was Re: IrDA spams logfiles - since 2.6.19)
Samuel Ortiz [Tue, 16 Jan 2007 03:37:25 +0000 (19:37 -0800)]
Since we stop using dev_alloc_skb on the IrDA TX frame, we constantly run
into the case of the skb headroom being 0, and thus we call skb_cow for
every IrDA TX frame.
This patch uses a local buffer and memcpy the skb to it, saving us a
kmalloc for each of those IrDA TX frames.

Signed-off-by: Samuel Ortiz <samuel@sortiz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/irda/irda-usb.c
drivers/net/irda/irda-usb.h

index 3ca1082..80cbf3f 100644 (file)
@@ -441,25 +441,13 @@ static int irda_usb_hard_xmit(struct sk_buff *skb, struct net_device *netdev)
                goto drop;
        }
 
-       /* Make sure there is room for IrDA-USB header. The actual
-        * allocation will be done lower in skb_push().
-        * Also, we don't use directly skb_cow(), because it require
-        * headroom >= 16, which force unnecessary copies - Jean II */
-       if (skb_headroom(skb) < self->header_length) {
-               IRDA_DEBUG(0, "%s(), Insuficient skb headroom.\n", __FUNCTION__);
-               if (skb_cow(skb, self->header_length)) {
-                       IRDA_WARNING("%s(), failed skb_cow() !!!\n", __FUNCTION__);
-                       goto drop;
-               }
-       }
+       memcpy(self->tx_buff + self->header_length, skb->data, skb->len);
 
        /* Change setting for next frame */
-
        if (self->capability & IUC_STIR421X) {
                __u8 turnaround_time;
-               __u8* frame;
+               __u8* frame = self->tx_buff;
                turnaround_time = get_turnaround_time( skb );
-               frame= skb_push(skb, self->header_length);
                irda_usb_build_header(self, frame, 0);
                frame[2] = turnaround_time;
                if ((skb->len != 0) &&
@@ -472,17 +460,17 @@ static int irda_usb_hard_xmit(struct sk_buff *skb, struct net_device *netdev)
                        frame[1] = 0;
                }
        } else {
-               irda_usb_build_header(self, skb_push(skb, self->header_length), 0);
+               irda_usb_build_header(self, self->tx_buff, 0);
        }
 
        /* FIXME: Make macro out of this one */
        ((struct irda_skb_cb *)skb->cb)->context = self;
 
-        usb_fill_bulk_urb(urb, self->usbdev, 
+       usb_fill_bulk_urb(urb, self->usbdev,
                      usb_sndbulkpipe(self->usbdev, self->bulk_out_ep),
-                      skb->data, IRDA_SKB_MAX_MTU,
+                      self->tx_buff, skb->len + self->header_length,
                       write_bulk_callback, skb);
-       urb->transfer_buffer_length = skb->len;
+
        /* This flag (URB_ZERO_PACKET) indicates that what we send is not
         * a continuous stream of data but separate packets.
         * In this case, the USB layer will insert an empty USB frame (TD)
@@ -1455,6 +1443,9 @@ static inline void irda_usb_close(struct irda_usb_cb *self)
        /* Remove the speed buffer */
        kfree(self->speed_buff);
        self->speed_buff = NULL;
+
+       kfree(self->tx_buff);
+       self->tx_buff = NULL;
 }
 
 /********************** USB CONFIG SUBROUTINES **********************/
@@ -1753,9 +1744,14 @@ static int irda_usb_probe(struct usb_interface *intf,
 
        memset(self->speed_buff, 0, IRDA_USB_SPEED_MTU);
 
+       self->tx_buff = kzalloc(IRDA_SKB_MAX_MTU + self->header_length,
+                               GFP_KERNEL);
+       if (self->tx_buff == NULL)
+               goto err_out_4;
+
        ret = irda_usb_open(self);
        if (ret) 
-               goto err_out_4;
+               goto err_out_5;
 
        IRDA_MESSAGE("IrDA: Registered device %s\n", net->name);
        usb_set_intfdata(intf, self);
@@ -1766,14 +1762,14 @@ static int irda_usb_probe(struct usb_interface *intf,
                self->needspatch = (ret < 0);
                if (self->needspatch) {
                        IRDA_ERROR("STIR421X: Couldn't upload patch\n");
-                       goto err_out_5;
+                       goto err_out_6;
                }
 
                /* replace IrDA class descriptor with what patched device is now reporting */
                irda_desc = irda_usb_find_class_desc (self->usbintf);
                if (irda_desc == NULL) {
                        ret = -ENODEV;
-                       goto err_out_5;
+                       goto err_out_6;
                }
                if (self->irda_desc)
                        kfree (self->irda_desc);
@@ -1782,9 +1778,10 @@ static int irda_usb_probe(struct usb_interface *intf,
        }
 
        return 0;
-
-err_out_5:
+err_out_6:
        unregister_netdev(self->netdev);
+err_out_5:
+       kfree(self->tx_buff);
 err_out_4:
        kfree(self->speed_buff);
 err_out_3:
index 6b2271f..e846c38 100644 (file)
@@ -156,6 +156,7 @@ struct irda_usb_cb {
        struct irlap_cb   *irlap;       /* The link layer we are binded to */
        struct qos_info qos;
        char *speed_buff;               /* Buffer for speed changes */
+       char *tx_buff;
 
        struct timeval stamp;
        struct timeval now;