Commit 6e583ce5 authored by Stephen Hemminger's avatar Stephen Hemminger Committed by David S. Miller

net: eliminate refcounting in backlog queue

Avoid the overhead of atomic increment/decrement on each received packet.
This helps performance of non-NAPI devices (like loopback).
Use cleanup function to walk queue on each cpu and clean out any
left over packets.
Signed-off-by: default avatarStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 283d07ac
...@@ -1909,7 +1909,6 @@ int netif_rx(struct sk_buff *skb) ...@@ -1909,7 +1909,6 @@ int netif_rx(struct sk_buff *skb)
if (queue->input_pkt_queue.qlen <= netdev_max_backlog) { if (queue->input_pkt_queue.qlen <= netdev_max_backlog) {
if (queue->input_pkt_queue.qlen) { if (queue->input_pkt_queue.qlen) {
enqueue: enqueue:
dev_hold(skb->dev);
__skb_queue_tail(&queue->input_pkt_queue, skb); __skb_queue_tail(&queue->input_pkt_queue, skb);
local_irq_restore(flags); local_irq_restore(flags);
return NET_RX_SUCCESS; return NET_RX_SUCCESS;
...@@ -2270,6 +2269,20 @@ int netif_receive_skb(struct sk_buff *skb) ...@@ -2270,6 +2269,20 @@ int netif_receive_skb(struct sk_buff *skb)
return ret; return ret;
} }
/* Network device is going away, flush any packets still pending */
static void flush_backlog(void *arg)
{
struct net_device *dev = arg;
struct softnet_data *queue = &__get_cpu_var(softnet_data);
struct sk_buff *skb, *tmp;
skb_queue_walk_safe(&queue->input_pkt_queue, skb, tmp)
if (skb->dev == dev) {
__skb_unlink(skb, &queue->input_pkt_queue);
kfree_skb(skb);
}
}
static int process_backlog(struct napi_struct *napi, int quota) static int process_backlog(struct napi_struct *napi, int quota)
{ {
int work = 0; int work = 0;
...@@ -2279,7 +2292,6 @@ static int process_backlog(struct napi_struct *napi, int quota) ...@@ -2279,7 +2292,6 @@ static int process_backlog(struct napi_struct *napi, int quota)
napi->weight = weight_p; napi->weight = weight_p;
do { do {
struct sk_buff *skb; struct sk_buff *skb;
struct net_device *dev;
local_irq_disable(); local_irq_disable();
skb = __skb_dequeue(&queue->input_pkt_queue); skb = __skb_dequeue(&queue->input_pkt_queue);
...@@ -2288,14 +2300,9 @@ static int process_backlog(struct napi_struct *napi, int quota) ...@@ -2288,14 +2300,9 @@ static int process_backlog(struct napi_struct *napi, int quota)
local_irq_enable(); local_irq_enable();
break; break;
} }
local_irq_enable(); local_irq_enable();
dev = skb->dev;
netif_receive_skb(skb); netif_receive_skb(skb);
dev_put(dev);
} while (++work < quota && jiffies == start_time); } while (++work < quota && jiffies == start_time);
return work; return work;
...@@ -4169,6 +4176,8 @@ void netdev_run_todo(void) ...@@ -4169,6 +4176,8 @@ void netdev_run_todo(void)
dev->reg_state = NETREG_UNREGISTERED; dev->reg_state = NETREG_UNREGISTERED;
on_each_cpu(flush_backlog, dev, 1);
netdev_wait_allrefs(dev); netdev_wait_allrefs(dev);
/* paranoia */ /* paranoia */
......
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