[ltt-dev] net isntrumentation: duplicated receive

Mathieu Desnoyers mathieu.desnoyers at efficios.com
Fri Oct 22 16:26:22 EDT 2010

Hi Benjamin,

Can you explain why you need two receive tracepoints in the recv path ?

"The receive tracepoint is moved earlier in the netif_receive_skb() function.
The tracepoint is also duplicated in the netif_rx() function. This enables
more precise measurements for pre-NAPI drivers."

@@ -2518,9 +2520,13 @@ int netif_rx(struct sk_buff *skb)
        if (netpoll_rx(skb))
                return NET_RX_DROP;
+       trace_net_dev_receive(skb);
        if (netdev_tstamp_prequeue)
+       trace_net_dev_receive(skb);

The side-effect is that two events will be generated for each packet, no ?



Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.

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