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Date: Thu, 15 Apr 2010 05:28:53 +0200 From: Eric Dumazet <eric.dumazet@...il.com> To: Changli Gao <xiaosuo@...il.com> Cc: "David S. Miller" <davem@...emloft.net>, Tom Herbert <therbert@...gle.com>, netdev@...r.kernel.org Subject: Re: [PATCH] net: fix softnet_stat Le jeudi 15 avril 2010 à 11:01 +0800, Changli Gao a écrit : > fix softnet_stat > > Per cpu variable softnet_data.total was shared between IRQ and SoftIRQ context > without any protection. And enqueue_to_backlog should update the netdev_rx_stat > of the target CPU. > > This patch changes the meaning of softnet_data.total to the number of packets > processed, not includes dropped, in order to avoid it sharing between IRQ and > SoftIRQ. And softnet_data.dropped is protected in the corresponding > input_pkt_queue.lock, if RPS is enabled. > > Signed-off-by: Changli Gao <xiaosuo@...il.com> > ---- > net/core/dev.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > diff --git a/net/core/dev.c b/net/core/dev.c > index a10a216..b38a991 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -2336,7 +2336,6 @@ static int enqueue_to_backlog(struct sk_buff *skb, int cpu) > queue = &per_cpu(softnet_data, cpu); > > local_irq_save(flags); > - __get_cpu_var(netdev_rx_stat).total++; I think this was nice, because we can see number of frames received by this cpu, before giving them to another cpu. Maybe we want a new counter ? __get_cpu_var(netdev_rx_stat).inpackets++; > > rps_lock(queue); > if (queue->input_pkt_queue.qlen <= netdev_max_backlog) { > @@ -2366,9 +2365,9 @@ enqueue: > goto enqueue; > } > > + per_cpu(netdev_rx_stat, cpu).dropped++; This is a bit expensive, and could be a queue->rx_stat.dropped++ if netdev_rx_stat is moved inside queue structure. > rps_unlock(queue); > > - __get_cpu_var(netdev_rx_stat).dropped++; > local_irq_restore(flags); > > kfree_skb(skb); > @@ -3565,7 +3564,7 @@ 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 %08x\n", > - s->total, s->dropped, s->time_squeeze, 0, > + s->total + s->dropped, s->dropped, s->time_squeeze, 0, This is wrong I believe... I prefer to add a new column, s->inpackets ? > 0, 0, 0, 0, /* was fastroute */ > s->cpu_collision, s->received_rps); > return 0; > -- -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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