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authorStephen Hemminger <shemminger@osdl.org>2005-06-24 07:12:48 +0400
committerDavid S. Miller <davem@davemloft.net>2005-06-24 07:12:48 +0400
commit31aa02c53c84658f6694f319f09e232ede27be5a (patch)
tree3af5cce958dcce744548b312a043aa4a0b769a50 /net
parent34008d8c631d067caffa136313260525f3ae48a2 (diff)
downloadlinux-31aa02c53c84658f6694f319f09e232ede27be5a.tar.xz
[NET]: Eliminate netif_rx massive packet drops.
Eliminate the throttling behaviour when the netif receive queue fills because it behaves badly when using high speed networks under load. The throttling cause multiple packet drops that cause TCP to go into slow start mode. The same effective patch has been part of BIC TCP and H-TCP as well as part of Web100. The existing code drops 100's of packets when the queue fills; this changes it to individual packet drop-tail. Signed-off-by: Stephen Hemmminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/dev.c21
1 files changed, 2 insertions, 19 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 3156df699f01..1a64508e527f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -198,7 +198,7 @@ static struct notifier_block *netdev_chain;
* Device drivers call our routines to queue packets here. We empty the
* queue in the local softnet handler.
*/
-DEFINE_PER_CPU(struct softnet_data, softnet_data) = { 0, };
+DEFINE_PER_CPU(struct softnet_data, softnet_data) = { NULL };
#ifdef CONFIG_SYSFS
extern int netdev_sysfs_init(void);
@@ -1372,7 +1372,6 @@ DEFINE_PER_CPU(struct netif_rx_stats, netdev_rx_stat) = { 0, };
int netif_rx(struct sk_buff *skb)
{
- int this_cpu;
struct softnet_data *queue;
unsigned long flags;
@@ -1388,15 +1387,11 @@ int netif_rx(struct sk_buff *skb)
* short when CPU is congested, but is still operating.
*/
local_irq_save(flags);
- this_cpu = smp_processor_id();
queue = &__get_cpu_var(softnet_data);
__get_cpu_var(netdev_rx_stat).total++;
if (queue->input_pkt_queue.qlen <= netdev_max_backlog) {
if (queue->input_pkt_queue.qlen) {
- if (queue->throttle)
- goto drop;
-
enqueue:
dev_hold(skb->dev);
__skb_queue_tail(&queue->input_pkt_queue, skb);
@@ -1404,19 +1399,10 @@ enqueue:
return NET_RX_SUCCESS;
}
- if (queue->throttle)
- queue->throttle = 0;
-
netif_rx_schedule(&queue->backlog_dev);
goto enqueue;
}
- if (!queue->throttle) {
- queue->throttle = 1;
- __get_cpu_var(netdev_rx_stat).throttled++;
- }
-
-drop:
__get_cpu_var(netdev_rx_stat).dropped++;
local_irq_restore(flags);
@@ -1701,8 +1687,6 @@ job_done:
smp_mb__before_clear_bit();
netif_poll_enable(backlog_dev);
- if (queue->throttle)
- queue->throttle = 0;
local_irq_enable();
return 0;
}
@@ -1976,7 +1960,7 @@ static int softnet_seq_show(struct seq_file *seq, void *v)
struct netif_rx_stats *s = v;
seq_printf(seq, "%08x %08x %08x %08x %08x %08x %08x %08x %08x\n",
- s->total, s->dropped, s->time_squeeze, s->throttled,
+ s->total, s->dropped, s->time_squeeze, 0,
0, 0, 0, 0, /* was fastroute */
s->cpu_collision );
return 0;
@@ -3220,7 +3204,6 @@ static int __init net_dev_init(void)
queue = &per_cpu(softnet_data, i);
skb_queue_head_init(&queue->input_pkt_queue);
- queue->throttle = 0;
queue->completion_queue = NULL;
INIT_LIST_HEAD(&queue->poll_list);
set_bit(__LINK_STATE_START, &queue->backlog_dev.state);