From 41852497a9205964b958a245a9526040b980926f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 26 Aug 2016 12:50:39 -0700 Subject: [PATCH] net: batch calls to flush_all_backlogs() After commit 145dd5f9c88f ("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 Acked-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- net/core/dev.c | 32 ++++++++++++-------------------- 1 file changed, 12 insertions(+), 20 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 1d5c6dda1988..34b5322bc081 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4282,18 +4282,11 @@ int netif_receive_skb(struct sk_buff *skb) } EXPORT_SYMBOL(netif_receive_skb); -struct flush_work { - struct net_device *dev; - struct work_struct work; -}; - -DEFINE_PER_CPU(struct flush_work, flush_works); +DEFINE_PER_CPU(struct work_struct, flush_works); /* Network device is going away, flush any packets still pending */ 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 softnet_data *sd; @@ -4303,7 +4296,7 @@ static void flush_backlog(struct work_struct *work) local_irq_disable(); rps_lock(sd); 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); kfree_skb(skb); input_queue_head_incr(sd); @@ -4313,7 +4306,7 @@ static void flush_backlog(struct work_struct *work) local_irq_enable(); 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); kfree_skb(skb); input_queue_head_incr(sd); @@ -4322,22 +4315,18 @@ static void flush_backlog(struct work_struct *work) local_bh_enable(); } -static void flush_all_backlogs(struct net_device *dev) +static void flush_all_backlogs(void) { unsigned int cpu; get_online_cpus(); - for_each_online_cpu(cpu) { - struct flush_work *flush = 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) + queue_work_on(cpu, system_highpri_wq, + per_cpu_ptr(&flush_works, 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(); } @@ -6725,8 +6714,8 @@ static void rollback_registered_many(struct list_head *head) unlist_netdevice(dev); dev->reg_state = NETREG_UNREGISTERING; - flush_all_backlogs(dev); } + flush_all_backlogs(); synchronize_net(); @@ -8291,8 +8280,11 @@ static int __init net_dev_init(void) */ for_each_possible_cpu(i) { + struct work_struct *flush = per_cpu_ptr(&flush_works, 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->process_queue); INIT_LIST_HEAD(&sd->poll_list); -- 2.20.1