Re: [PATCH v2] net: reimplement softnet_data.output_queue as a FIFO queue

[Eric Dumazet <eric.dumazet@gmail.com>]

Le mardi 27 avril 2010 à 17:06 +0800, Changli Gao a écrit :
> reimplement softnet_data.output_queue as a FIFO queue.
> 
> reimplement softnet_data.output_queue as a FIFO queue to keep the fairness among
> the qdiscs rescheduled.
> 
> Signed-off-by: Changli Gao <xiaosuo@gmail.com>

Acked-by: Eric Dumazet <eric.dumazet@gmail.com>

> ----
>  include/linux/netdevice.h |    1 +
>  net/core/dev.c            |   22 ++++++++++++----------
>  2 files changed, 13 insertions(+), 10 deletions(-)
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 3c5ed5f..c04ca24 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -1385,6 +1385,7 @@ static inline int unregister_gifconf(unsigned int family)
>   */
>  struct softnet_data {
>  	struct Qdisc		*output_queue;
> +	struct Qdisc		**output_queue_tailp;
>  	struct list_head	poll_list;
>  	struct sk_buff		*completion_queue;
>  
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 4d43f1a..3d31491 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -1557,8 +1557,9 @@ static inline void __netif_reschedule(struct Qdisc *q)
>  
>  	local_irq_save(flags);
>  	sd = &__get_cpu_var(softnet_data);
> -	q->next_sched = sd->output_queue;
> -	sd->output_queue = q;
> +	q->next_sched = NULL;
> +	*sd->output_queue_tailp = q;
> +	sd->output_queue_tailp = &q->next_sched;
>  	raise_softirq_irqoff(NET_TX_SOFTIRQ);
>  	local_irq_restore(flags);
>  }
> @@ -2529,6 +2530,7 @@ static void net_tx_action(struct softirq_action *h)
>  		local_irq_disable();
>  		head = sd->output_queue;
>  		sd->output_queue = NULL;
> +		sd->output_queue_tailp = &sd->output_queue;
>  		local_irq_enable();
>  
>  		while (head) {
> @@ -5594,7 +5596,6 @@ static int dev_cpu_callback(struct notifier_block *nfb,
>  			    void *ocpu)
>  {
>  	struct sk_buff **list_skb;
> -	struct Qdisc **list_net;
>  	struct sk_buff *skb;
>  	unsigned int cpu, oldcpu = (unsigned long)ocpu;
>  	struct softnet_data *sd, *oldsd;
> @@ -5615,13 +5616,13 @@ static int dev_cpu_callback(struct notifier_block *nfb,
>  	*list_skb = oldsd->completion_queue;
>  	oldsd->completion_queue = NULL;
>  
> -	/* Find end of our output_queue. */
> -	list_net = &sd->output_queue;
> -	while (*list_net)
> -		list_net = &(*list_net)->next_sched;
>  	/* Append output queue from offline CPU. */
> -	*list_net = oldsd->output_queue;
> -	oldsd->output_queue = NULL;
> +	if (oldsd->output_queue) {
> +		*sd->output_queue_tailp = oldsd->output_queue;
> +		sd->output_queue_tailp = oldsd->output_queue_tailp;
> +		oldsd->output_queue = NULL;
> +		oldsd->output_queue_tailp = &oldsd->output_queue;
> +	}
>  
>  	raise_softirq_irqoff(NET_TX_SOFTIRQ);
>  	local_irq_enable();
> @@ -5851,7 +5852,8 @@ static int __init net_dev_init(void)
>  		skb_queue_head_init(&sd->input_pkt_queue);
>  		sd->completion_queue = NULL;
>  		INIT_LIST_HEAD(&sd->poll_list);
> -
> +		sd->output_queue = NULL;
> +		sd->output_queue_tailp = &sd->output_queue;
>  #ifdef CONFIG_RPS
>  		sd->csd.func = rps_trigger_softirq;
>  		sd->csd.info = sd;
> --
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