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linux-sg2042
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net: batch calls to flush_all_backlogs() 

After commit 145dd5f9c8 ("net: flush the softnet backlog in process
context"), we can easily batch calls to flush_all_backlogs() for all
devices processed in rollback_registered_many()

Tested:

Before patch, on an idle host.

modprobe dummy numdummies=10000
perf stat -e context-switches -a rmmod dummy

 Performance counter stats for 'system wide':

         1,211,798      context-switches

       1.302137465 seconds time elapsed

After patch:

perf stat -e context-switches -a rmmod dummy

 Performance counter stats for 'system wide':

           225,523      context-switches

       0.721623566 seconds time elapsed

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2016-08-26 12:50:39 -07:00 committed by David S. Miller
parent ae3cb8cb20
commit 41852497a9
1 changed files with 12 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
net/core/dev.c
View File

@ -4282,18 +4282,11 @@ int netif_receive_skb(struct sk_buff *skb)
} }
EXPORT_SYMBOL(netif_receive_skb); EXPORT_SYMBOL(netif_receive_skb);
struct flush_work { DEFINE_PER_CPU(struct work_struct, flush_works);
struct net_device *dev;
struct work_struct work;
};
DEFINE_PER_CPU(struct flush_work, flush_works);
/* Network device is going away, flush any packets still pending */ /* Network device is going away, flush any packets still pending */
static void flush_backlog(struct work_struct *work) static void flush_backlog(struct work_struct *work)
{ {
struct flush_work *flush = container_of(work, typeof(*flush), work);
struct net_device *dev = flush->dev;
struct sk_buff *skb, *tmp; struct sk_buff *skb, *tmp;
struct softnet_data *sd; struct softnet_data *sd;
@ -4303,7 +4296,7 @@ static void flush_backlog(struct work_struct *work)
local_irq_disable(); local_irq_disable();
rps_lock(sd); rps_lock(sd);
skb_queue_walk_safe(&sd->input_pkt_queue, skb, tmp) { skb_queue_walk_safe(&sd->input_pkt_queue, skb, tmp) {
if (skb->dev == dev) { if (skb->dev->reg_state == NETREG_UNREGISTERING) {
__skb_unlink(skb, &sd->input_pkt_queue); __skb_unlink(skb, &sd->input_pkt_queue);
kfree_skb(skb); kfree_skb(skb);
input_queue_head_incr(sd); input_queue_head_incr(sd);
@ -4313,7 +4306,7 @@ static void flush_backlog(struct work_struct *work)
local_irq_enable(); local_irq_enable();
skb_queue_walk_safe(&sd->process_queue, skb, tmp) { skb_queue_walk_safe(&sd->process_queue, skb, tmp) {
if (skb->dev == dev) { if (skb->dev->reg_state == NETREG_UNREGISTERING) {
__skb_unlink(skb, &sd->process_queue); __skb_unlink(skb, &sd->process_queue);
kfree_skb(skb); kfree_skb(skb);
input_queue_head_incr(sd); input_queue_head_incr(sd);
@ -4322,22 +4315,18 @@ static void flush_backlog(struct work_struct *work)
local_bh_enable(); local_bh_enable();
} }
static void flush_all_backlogs(struct net_device *dev) static void flush_all_backlogs(void)
{ {
unsigned int cpu; unsigned int cpu;
get_online_cpus(); get_online_cpus();
for_each_online_cpu(cpu) { for_each_online_cpu(cpu)
struct flush_work *flush = per_cpu_ptr(&flush_works, cpu); queue_work_on(cpu, system_highpri_wq,
per_cpu_ptr(&flush_works, cpu));
INIT_WORK(&flush->work, flush_backlog);
flush->dev = dev;
queue_work_on(cpu, system_highpri_wq, &flush->work);
}
for_each_online_cpu(cpu) for_each_online_cpu(cpu)
flush_work(&per_cpu_ptr(&flush_works, cpu)->work); flush_work(per_cpu_ptr(&flush_works, cpu));
put_online_cpus(); put_online_cpus();
} }
@ -6725,8 +6714,8 @@ static void rollback_registered_many(struct list_head *head)
unlist_netdevice(dev); unlist_netdevice(dev);
dev->reg_state = NETREG_UNREGISTERING; dev->reg_state = NETREG_UNREGISTERING;
flush_all_backlogs(dev);
} }
flush_all_backlogs();
synchronize_net(); synchronize_net();
@ -8291,8 +8280,11 @@ static int __init net_dev_init(void)
*/ */
for_each_possible_cpu(i) { for_each_possible_cpu(i) {
struct work_struct *flush = per_cpu_ptr(&flush_works, i);
struct softnet_data *sd = &per_cpu(softnet_data, i); struct softnet_data *sd = &per_cpu(softnet_data, i);
INIT_WORK(flush, flush_backlog);
skb_queue_head_init(&sd->input_pkt_queue); skb_queue_head_init(&sd->input_pkt_queue);
skb_queue_head_init(&sd->process_queue); skb_queue_head_init(&sd->process_queue);
INIT_LIST_HEAD(&sd->poll_list); INIT_LIST_HEAD(&sd->poll_list);