On Tue, Sep 6, 2016 at 9:32 PM, Francis Y. Yan <francisy...@gmail.com> wrote: > > To export useful TCP statistics along with timestamps, such as > rwnd-limited time and min RTT, we enqueue a TLV list in error queue > immediately when a timestamp is generated. > > Specifically, if user space requests SOF_TIMESTAMPING_TX_* timestamps > and sets SOF_TIMESTAMPING_OPT_STATS, the kernel will create a list of > TLVs (struct nlattr) containing all the statistics and store the list > in payload of the skb that is going to be enqueued into error queue. > Notice that SOF_TIMESTAMPING_OPT_STATS can only be set together with > SOF_TIMESTAMPING_OPT_TSONLY. > > In addition, if the application in user space also enables receiving > timestamp (e.g. by SOF_TIMESTAMPING_SOFTWARE), calling recvfrom() on > error queue will return one more control message with a cmsg_type of > SCM_OPT_STATS containing the list of TLVs in its cmsg_data. > > Signed-off-by: Francis Y. Yan <francisy...@gmail.com> > Signed-off-by: Yuchung Cheng <ych...@google.com>
Acked-by: Soheil Hassas Yeganeh <soh...@google.com>
