If you queued a message right now, approximately how long would that message
wait in the queue before we actually started putting its data on the wire in
a packet?
In general, data that is sent by the application is limited by the bandwidth
of the channel. If you send data faster than this, it must be queued and
put on the wire at a metered rate. Even sending a small amount of data (e.g.
a few MTU, say ~3k) will require some of the data to be delayed a bit.
Ignoring multiple lanes, the estimated delay will be approximately equal to
plus or minus one MTU. It depends on how much time has elapsed since the last
packet was put on the wire. For example, the queue might have *just* been emptied,
and the last packet placed on the wire, and we are exactly up against the send
rate limit. In that case we might need to wait for one packet's worth of time to
elapse before we can send again. On the other extreme, the queue might have data
in it waiting for Nagle. (This will always be less than one packet, because as
soon as we have a complete packet we would send it.) In that case, we might be
ready to send data now, and this value will be -1.
This value is only valid if multiple lanes are not used. If multiple lanes are
in use, then the queue time will be different for each lane, and you must use
the value in SteamNetConnectionRealTimeLaneStatus_t.
Nagle delay is ignored for the purposes of this calculation.
If you queued a message right now, approximately how long would that message wait in the queue before we actually started putting its data on the wire in a packet?
In general, data that is sent by the application is limited by the bandwidth of the channel. If you send data faster than this, it must be queued and put on the wire at a metered rate. Even sending a small amount of data (e.g. a few MTU, say ~3k) will require some of the data to be delayed a bit.
Ignoring multiple lanes, the estimated delay will be approximately equal to
( m_cbPendingUnreliable+m_cbPendingReliable ) / m_nSendRateBytesPerSecond
plus or minus one MTU. It depends on how much time has elapsed since the last packet was put on the wire. For example, the queue might have *just* been emptied, and the last packet placed on the wire, and we are exactly up against the send rate limit. In that case we might need to wait for one packet's worth of time to elapse before we can send again. On the other extreme, the queue might have data in it waiting for Nagle. (This will always be less than one packet, because as soon as we have a complete packet we would send it.) In that case, we might be ready to send data now, and this value will be -1.
This value is only valid if multiple lanes are not used. If multiple lanes are in use, then the queue time will be different for each lane, and you must use the value in SteamNetConnectionRealTimeLaneStatus_t.
Nagle delay is ignored for the purposes of this calculation.