In order to reduce the interrupt times in the embedded system,
a receiving workqueue is introduced.
This modification also enhanced the overall throughput as the
benefits of reducing interrupt occurrence.
This work was derived from previous work:
u_ether: move hardware transmit to RX workqueue.
Which should be base on codeaurora's work.
However, the benchmark on my platform shows the throughput
with workqueue is slightly better than NAPI.
Signed-off-by: Weinn Jheng <clanlab.proj@xxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Stephen Hemminger <shemminger@xxxxxxxxxx>
Cc: Felipe Balbi <balbi@xxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Manu Gautam <mgautam@xxxxxxxxxxxxxx>
Cc: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
---
Changes for v2:
- Trying to fix the plug/unplug problem which cause KE.
Changes for v3:
- Fix plug/unplug problem in gether_disconenct.
- Refine the rx/tx_completion function assigment.
- This patch has been tested on beaglebone black.
Changes for v4:
- Move NAPI disable to a work queue and see if this won't cause KE
on replug.
drivers/usb/gadget/u_ether.c | 138 ++++++++++++++++++++++++++++++-------------
1 file changed, 98 insertions(+), 40 deletions(-)
diff --git a/drivers/usb/gadget/u_ether.c b/drivers/usb/gadget/u_ether.c
index 97b0277..785d018 100644
--- a/drivers/usb/gadget/u_ether.c
+++ b/drivers/usb/gadget/u_ether.c
@@ -48,6 +48,8 @@
#define UETH__VERSION "29-May-2008"
+#define GETHER_NAPI_WEIGHT 5
+
struct eth_dev {
/* lock is held while accessing port_usb
*/
@@ -72,6 +74,8 @@ struct eth_dev {
struct sk_buff_head *list);
struct work_struct work;
+ struct work_struct napi_work;
+ struct napi_struct rx_napi;
unsigned long todo;
#define WORK_RX_MEMORY 0
@@ -187,6 +191,7 @@ static void defer_kevent(struct eth_dev *dev, int flag)
}
static void rx_complete(struct usb_ep *ep, struct usb_request *req);
+static void tx_complete(struct usb_ep *ep, struct usb_request *req);
static int
rx_submit(struct eth_dev *dev, struct usb_request *req, gfp_t gfp_flags)
@@ -242,7 +247,6 @@ rx_submit(struct eth_dev *dev, struct usb_request *req, gfp_t gfp_flags)
req->buf = skb->data;
req->length = size;
- req->complete = rx_complete;
req->context = skb;
retval = usb_ep_queue(out, req, gfp_flags);
@@ -253,18 +257,16 @@ enomem:
DBG(dev, "rx submit --> %d\n", retval);
if (skb)
dev_kfree_skb_any(skb);
- spin_lock_irqsave(&dev->req_lock, flags);
- list_add(&req->list, &dev->rx_reqs);
- spin_unlock_irqrestore(&dev->req_lock, flags);
}
return retval;
}
static void rx_complete(struct usb_ep *ep, struct usb_request *req)
{
- struct sk_buff *skb = req->context, *skb2;
+ struct sk_buff *skb = req->context;
struct eth_dev *dev = ep->driver_data;
int status = req->status;
+ bool rx_queue = 0;
switch (status) {
@@ -288,30 +290,8 @@ static void rx_complete(struct usb_ep *ep, struct usb_request *req)
} else {
skb_queue_tail(&dev->rx_frames, skb);
}
- skb = NULL;
-
- skb2 = skb_dequeue(&dev->rx_frames);
- while (skb2) {
- if (status < 0
- || ETH_HLEN > skb2->len
- || skb2->len > VLAN_ETH_FRAME_LEN) {
- dev->net->stats.rx_errors++;
- dev->net->stats.rx_length_errors++;
- DBG(dev, "rx length %d\n", skb2->len);
- dev_kfree_skb_any(skb2);
- goto next_frame;
- }
- skb2->protocol = eth_type_trans(skb2, dev->net);
- dev->net->stats.rx_packets++;
- dev->net->stats.rx_bytes += skb2->len;
-
- /* no buffer copies needed, unless hardware can't
- * use skb buffers.
- */
- status = netif_rx(skb2);
-next_frame:
- skb2 = skb_dequeue(&dev->rx_frames);
- }
+ if (!status)
+ rx_queue = 1;
break;
/* software-driven interface shutdown */
@@ -334,28 +314,27 @@ quiesce:
/* FALLTHROUGH */
default:
+ rx_queue = 1;
+ dev_kfree_skb_any(skb);
dev->net->stats.rx_errors++;
DBG(dev, "rx status %d\n", status);
break;
}
- if (skb)
- dev_kfree_skb_any(skb);
- if (!netif_running(dev->net)) {
clean:
- spin_lock(&dev->req_lock);
- list_add(&req->list, &dev->rx_reqs);
- spin_unlock(&dev->req_lock);
- req = NULL;
- }
- if (req)
- rx_submit(dev, req, GFP_ATOMIC);
+ spin_lock(&dev->req_lock);
+ list_add(&req->list, &dev->rx_reqs);
+ spin_unlock(&dev->req_lock);
+
+ if (rx_queue && likely(napi_schedule_prep(&dev->rx_napi)))
+ __napi_schedule(&dev->rx_napi);
}
static int prealloc(struct list_head *list, struct usb_ep *ep, unsigned n)
{
unsigned i;
struct usb_request *req;
+ bool usb_in;
if (!n)
return -ENOMEM;
@@ -366,10 +345,22 @@ static int prealloc(struct list_head *list, struct usb_ep *ep, unsigned n)
if (i-- == 0)
goto extra;
}
+
+ if (ep->desc->bEndpointAddress & USB_DIR_IN)
+ usb_in = true;
+ else
+ usb_in = false;
+
while (i--) {
req = usb_ep_alloc_request(ep, GFP_ATOMIC);
if (!req)
return list_empty(list) ? -ENOMEM : 0;
+ /* update completion handler */
+ if (usb_in)
+ req->complete = tx_complete;
+ else
+ req->complete = rx_complete;
+
list_add(&req->list, list);
}
return 0;
@@ -414,16 +405,24 @@ static void rx_fill(struct eth_dev *dev, gfp_t gfp_flags)
{
struct usb_request *req;
unsigned long flags;
+ int rx_counts = 0;
/* fill unused rxq slots with some skb */
spin_lock_irqsave(&dev->req_lock, flags);
while (!list_empty(&dev->rx_reqs)) {
+
+ if (++rx_counts > qlen(dev->gadget, dev->qmult))
+ break;
+
req = container_of(dev->rx_reqs.next,
struct usb_request, list);
list_del_init(&req->list);
spin_unlock_irqrestore(&dev->req_lock, flags);
if (rx_submit(dev, req, gfp_flags) < 0) {
+ spin_lock_irqsave(&dev->req_lock, flags);
+ list_add(&req->list, &dev->rx_reqs);
+ spin_unlock_irqrestore(&dev->req_lock, flags);
defer_kevent(dev, WORK_RX_MEMORY);
return;
}
@@ -433,6 +432,51 @@ static void rx_fill(struct eth_dev *dev, gfp_t gfp_flags)
spin_unlock_irqrestore(&dev->req_lock, flags);
}
+static int gether_poll(struct napi_struct *napi, int budget)
+{
+ struct eth_dev *dev = container_of(napi, struct eth_dev, rx_napi);
+ struct sk_buff *skb;
+ unsigned int work_done = 0;
+ int status = 0;
+
+ if (!dev->port_usb)
+ return work_done;
+
+ while ((skb = skb_dequeue(&dev->rx_frames))) {
+ if (status < 0
+ || ETH_HLEN > skb->len
+ || skb->len > VLAN_ETH_FRAME_LEN) {
+ dev->net->stats.rx_errors++;
+ dev->net->stats.rx_length_errors++;
+ DBG(dev, "rx length %d\n", skb->len);
+ dev_kfree_skb_any(skb);
+ continue;
+ }
+ skb->protocol = eth_type_trans(skb, dev->net);
+ dev->net->stats.rx_packets++;
+ dev->net->stats.rx_bytes += skb->len;
+
+ status = netif_rx_ni(skb);
+ work_done++;
+ }
+
+ if (work_done < budget)
+ napi_complete(&dev->rx_napi);
+
+ /* put rx_fill here for avoiding running out rx_reqs */
+ if (netif_running(dev->net))
+ rx_fill(dev, GFP_KERNEL);
+
+ return work_done;
+}
+
+static void napi_disable_work(struct work_struct *work)
+{
+ struct eth_dev *dev = container_of(work, struct eth_dev, work);
+
+ napi_disable(&dev->rx_napi);
+}
+
static void eth_work(struct work_struct *work)
{
struct eth_dev *dev = container_of(work, struct eth_dev, work);
@@ -564,7 +608,6 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
}
req->buf = skb->data;
req->context = skb;
- req->complete = tx_complete;
/* NCM requires no zlp if transfer is dwNtbInMaxSize */
if (dev->port_usb->is_fixed &&
@@ -625,6 +668,7 @@ static void eth_start(struct eth_dev *dev, gfp_t gfp_flags)
/* and open the tx floodgates */
atomic_set(&dev->tx_qlen, 0);
netif_wake_queue(dev->net);
+ napi_enable(&dev->rx_napi);
}
static int eth_open(struct net_device *net)
@@ -651,6 +695,7 @@ static int eth_stop(struct net_device *net)
unsigned long flags;
VDBG(dev, "%s\n", __func__);
+ napi_disable(&dev->rx_napi);
netif_stop_queue(net);
DBG(dev, "stop stats: rx/tx %ld/%ld, errs %ld/%ld\n",
@@ -768,9 +813,11 @@ struct eth_dev *gether_setup_name(struct usb_gadget *g,
return ERR_PTR(-ENOMEM);
dev = netdev_priv(net);
+ netif_napi_add(net, &dev->rx_napi, gether_poll, GETHER_NAPI_WEIGHT);
spin_lock_init(&dev->lock);
spin_lock_init(&dev->req_lock);
INIT_WORK(&dev->work, eth_work);
+ INIT_WORK(&dev->napi_work, napi_disable_work);
INIT_LIST_HEAD(&dev->tx_reqs);
INIT_LIST_HEAD(&dev->rx_reqs);
@@ -830,6 +877,7 @@ struct net_device *gether_setup_name_default(const char *netname)
return ERR_PTR(-ENOMEM);
dev = netdev_priv(net);
+ netif_napi_add(net, &dev->rx_napi, gether_poll, GETHER_NAPI_WEIGHT);
spin_lock_init(&dev->lock);
spin_lock_init(&dev->req_lock);
INIT_WORK(&dev->work, eth_work);
@@ -1113,6 +1161,7 @@ void gether_disconnect(struct gether *link)
{
struct eth_dev *dev = link->ioport;
struct usb_request *req;
+ struct sk_buff *skb;
WARN_ON(!dev);
if (!dev)
@@ -1120,6 +1169,9 @@ void gether_disconnect(struct gether *link)
DBG(dev, "%s\n", __func__);
+ if (!schedule_work(&dev->napi_work))
+ ERROR(dev, "NAPI disable work cannot be scheduled\n");
+
netif_tx_lock(dev->net);
netif_stop_queue(dev->net);
netif_tx_unlock(dev->net);
@@ -1142,6 +1194,12 @@ void gether_disconnect(struct gether *link)
spin_lock(&dev->req_lock);
}
spin_unlock(&dev->req_lock);
+
+ spin_lock(&dev->rx_frames.lock);
+ while ((skb = __skb_dequeue(&dev->rx_frames)))
+ dev_kfree_skb_any(skb);
+ spin_unlock(&dev->rx_frames.lock);
+
link->in_ep->driver_data = NULL;
link->in_ep->desc = NULL;
--
1.9.1
--
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