OID_GEN_CO_NETCARD_LOAD

The OID_GEN_CO_NETCARD_LOAD OID returns the relative load on the transmit system of a connection-oriented miniport driver. The miniport driver derives this number by calculating the difference between the amount of data delivered for transmission from protocols and the amount of data actually sent, as indicated by the packets returned to protocols with NdisMCoSendComplete. The result is the amount of outstanding transmit data in the miniport driver at any time.

Because this statistic changes at a very high frequency, the miniport driver port should filter it. The simplest filtering method is to maintain a running average of samples of the outstanding transmit data. For example, each time MiniportCoSendPackets is called, the miniport driver could add the submitted packet size to a miniport driver-defined variable called OutstandingBytes. Each time the miniport driver calls NdisMCoSendComplete, the miniport driver would then subtract the returned packet size from OutstandingBytes. The miniport driver must also maintain a running average, which is the value that the miniport driver should return in response to the OID_GEN_CO_NETCARD_LOAD query. This variable, which could be called RunningAverage, must be updated on each MiniportCoSendPackets, as follows:

RunningAverage = [(RunningAverage * C) + (OutstandingBytes * (128 - C))] / 128;

In this case, 1 < C < 128. Larger values of C produce smoother filtering.

Requirements

Version: Windows Vista and later Header: Ntddndis.h (include Ndis.h)