NDIS_RECEIVE_SCALE_PARAMETERS_V2 structure (ntddndis.h)

Warning

Some information in this topic relates to prereleased product, which may be substantially modified before it's commercially released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

RSSv2 is preview only in Windows 10, version 1803.

The NDIS_RECEIVE_SCALE_PARAMETERS_V2 structure specifies the Receive Side Scaling (RSS) parameters for a miniport adapter that advertises support for RSS Version 2 (RSSv2). It is used in the OID_GEN_RECEIVE_SCALE_PARAMETERS_V2 OID.

Syntax

typedef struct _NDIS_RECEIVE_SCALE_PARAMETERS_V2 {
  NDIS_OBJECT_HEADER Header;
  ULONG              Flags;
  ULONG              HashInformation;
  ULONG              HashSecretKeySize;
  ULONG              HashSecretKeyOffset;
  ULONG              NumberOfQueues;
  ULONG              NumberOfIndirectionTableEntries;
} NDIS_RECEIVE_SCALE_PARAMETERS_V2, *PNDIS_RECEIVE_SCALE_PARAMETERS_V2;

Members

Header

The NDIS_OBJECT_HEADER structure for the NDIS_RECEIVE_SCALE_PARAMETERS_V2 structure. Set the Type member of the structure that Header specifies to NDIS_OBJECT_TYPE_RSS_PARAMETERS_V2.

For NDIS 6.80 and later drivers, set the Revision member to NDIS_RECEIVE_SCALE_PARAMETERS_V2_REVISION_1 and the Size member to sizeof(NDIS_RECEIVE_SCALE_PARAMETERS_V2).

Flags

A ULONG value that indicates which parameters are being changed. The driver can use these flags to quickly determine which parameters have changed and update the RSS settings accordingly.

In a query request, set this member to zero.

In a set request, the flags are defined as follows:

Value	Meaning
NDIS_RECEIVE_SCALE_PARAM_ENABLE_RSS	A value of 1 indicates that RSS is enabled for the specified object. The miniport driver needs to look at other parameters. A value of 0 indicates that RSS is disabled for the specified object. The NumberOfQueues and NumberOfIndirectionTableEntries parameters can change when RSS is disabled. Other parameters like HashInformation and HashKey should be ignored when RSS is disabled.
NDIS_RECEIVE_SCALE_PARAM_HASH_INFO_CHANGED	The value of the HashInformation parameter has changed.
NDIS_RECEIVE_SCALE_PARAM_HASH_KEY_CHANGED	The contents of the HashSecretKey member have changed.
NDIS_RECEIVE_SCALE_PARAM_NUMBER_OF_QUEUES_CHANGED	The number of queues per VPort has changed.
NDIS_RECEIVE_SCALE_PARAM_NUMBER_OF_ENTRIES_CHANGED	The number of entries in the indirection table has changed.

HashInformation

In a set request, this member is the hash type and hash function that the NIC should use to compute the hash values for the incoming packets. If the hash function that is specified within the HashInformation member is zero, RSS is disabled.

In a query request, this member is the hash type and hash function that the NIC is using.

Overlying drivers and NDIS can use the NDIS_RSS_HASH_INFO_FROM_TYPE_AND_FUNC macro to combine the hash type and hash function into hash information and set the HashInformation member.

Miniport drivers can use the NDIS_RSS_HASH_TYPE_FROM_HASH_INFO macro to get the hash type from HashInformation and the NDIS_RSS_HASH_FUNC_FROM_HASH_INFO macro to get the hash function.

This parameter can be changed at the same time that RSS is enabled, or afterward.

HashSecretKeySize

The size of the secret key array of the hash function, in bytes. The size of the array is 40 bytes for NdisHashFunctionToeplitz.

This parameter can be changed at the same time that RSS is enabled, or afterward.

HashSecretKeyOffset

The offset, in bytes, of the hash secret key.

This parameter can be changed at the same time that RSS is enabled, or afterward.

NumberOfQueues

The maximum number of queues for the scaling entity. This parameter is an alias for the NUM_QUEUE_PAIRS variable of the NDIS_NIC_SWITCH_VPORT_PARAMETERS structure, which can also be queried or set through the OID_NIC_SWITCH_VPORT_PARAMETERS OID. It can be changed when RSS is enabled or disabled.

NumberOfIndirectionTableEntries

The number of indirection table entries (ITEs) for the scaling entity. This value is a power of two and does not exceed the corresponding adapter's capabilities. It can be changed at the before RSS is enabled, or afterward.

New values for this parameter are also a power of two and do exceed adapter capabilities. When this number is increased, the miniport driver should clone the current indirection table into the new ITEs as many times as needed (this is possible because of the power-of-two restriction). When this number is decreased, the upper layer guarantees that the portion of the indirection table which is being removed contains exact replicas of the remaining portion.

Requirements

Requirement	Value
Minimum supported client	Supported in NDIS 6.80 and later.
Header	ntddndis.h (include Ndis.h)

See also

NDIS_NIC_SWITCH_VPORT_PARAMETERS

NDIS_OBJECT_HEADER

NDIS_RSS_HASH_FUNC_FROM_HASH_INFO

NDIS_RSS_HASH_INFO_FROM_TYPE_AND_FUNC

NDIS_RSS_HASH_TYPE_FROM_HASH_INFO

OID_GEN_RECEIVE_SCALE_PARAMETERS_V2

OID_NIC_SWITCH_VPORT_PARAMETERS

RSS Version 2 (RSSv2)