CODEWITHSUNDEEP
lttng
AlanObject
AlanObject

Reputation: 9973

Descriptions of lttng kernel events

I have just started to explore using LTTng to diagnose a network performance problem and it looks like a great tool to use for this. I know I can get a list of events I can capture with lttng list -k but I can't find any documentation on what the events mean.

For example since I am interested in networking performance of an application it looks like I am interested in the events: 

  net_dev_xmit (loglevel: TRACE_EMERG (0)) (type: tracepoint)
  net_dev_queue (loglevel: TRACE_EMERG (0)) (type: tracepoint)
  netif_receive_skb (loglevel: TRACE_EMERG (0)) (type: tracepoint)
  netif_rx (loglevel: TRACE_EMERG (0)) (type: tracepoint)

I can pretty much intuit what the difference between net_dev_xmit and net_dev_queue is, but what does netif_recieve_skb mean?

This is with Ubuntu 12.04 LTS.

If it turns out that the documentation is just the kernel source code then so be it -- but I didn't want to dig into that if a reference for this was somewhere around and i missed it.

Upvotes: 2

Views: 865

Answers (1)

Suchakra
Suchakra

Reputation: 33

I don't know if you are still interested, but just for the sake of completion, netif_recieve_skb tracepoint is in the netif_recieve_skb() function in the kernel. It's basically used to notify the kernel that a packet has being received and is in the socket buffer. It is similar to netif_rx() but is supposed to be used only by NAPI-compliant drivers. What the tracepoint in the function records can be seen here. Basically it's just some relevant stuff from the sk_buff struct.

Upvotes: 3

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