PFND3DDDI_CHECKCOUNTER callback function

Description

PFND3DDDI_CHECKCOUNTER is called by the Direct3D runtime to retrieve info that describes a counter. Must be implemented by Windows Display Driver Model (WDDM) 1.3 and later user-mode display drivers.

Parameters

hDevice

[in] A handle to the display device (graphics context).

unnamedParam2

[in] Counter is a value of type D3DDDIQUERYTYPE that identifies the counter identifier that info is retrieved for.

unnamedParam3

[out] pType is a pointer to a variable that receives a D3DDDI_COUNTER_TYPE enumeration value that identifies the data type that the counter outputs.

unnamedParam4

pActiveCounters [out] pActiveCounters is a pointer to a variable that receives the number of simultaneously active counters that are allocated for the creation of the counter identifier that the Counter parameter identifies.

unnamedParam5

[out, optional] pszName is an optional pointer that the driver returns a NULL-terminated string to that contains the name of the counter identifier.

Can be NULL, in which case the app doesn't need the name.

pNameLength

[in, out, optional] An optional pointer to a variable that receives the size, in bytes, of the NULL-terminated string that the pszName parameter specifies.

Here are limitations on the values of the pNameLength and pszName parameters:

• pNameLength can be NULL, in which case the app doesn't need the name or name length.
• If pszName is NULL and pNameLength is not NULL, the input value of pNameLength is ignored, and the length of the string (including terminating NULL character) must be returned through the pNameLength parameter.
• If both pszName and pNameLength are not NULL, the driver must check the input value of pNameLength to ensure that there's enough room in the allocated buffer, and then the length of the pszName string (including terminating NULL character) is passed out through the pNameLength parameter.

unnamedParam7

[out, optional] pszUnits is an optional pointer that the driver returns a NULL-terminated string to that contains the name of the units that the counter identifier measures.

Can be NULL, in which case the app doesn't need the units info. See more info in the explanation of the pUnitsLength parameter.

pUnitsLength

[in, out, optional] pUnitsLength is an optional pointer to a variable that receives the size, in bytes, of the NULL-terminated string that the pszUnits parameter specifies.

Here are limitations on the values of the pUnitsLength and pszUnits parameters:

• pUnitsLength can be NULL, in which case the app doesn't need the unit name or unit name length.
• If pszUnits is NULL and pUnitsLength is not NULL, the input value of pUnitsLength is ignored, and the length of the string (including terminating NULL character) must be returned through the pUnitsLength parameter.
• If both pszUnits and pUnitsLength are not NULL, the driver must check the input value of pUnitsLength to ensure that there's enough room in the allocated buffer, and then the length of the pszUnits string (including terminating NULL character) is passed out through the pUnitsLength parameter.

unnamedParam9

[out, optional] pszDescription is an optional pointer that the driver returns a NULL-terminated string to that contains the description of what the counter identifier measures.

Can be NULL, in which case the app doesn't need the description info. See more info in the explanation of the pDescriptionLength parameter.

pDescriptionLength

[in, out, optional] pDescriptionLength is an optional pointer to a variable that receives the size, in bytes, of the NULL-terminated string that the pszDescription parameter specifies.

Here are limitations on the values of the pDescriptionLength and pszDescription parameters:

• pDescriptionLength can be NULL, in which case the app doesn't need the unit name or unit name length.
• If pszDescription is NULL and pDescriptionLength is not NULL, the input value of pDescriptionLength is ignored, and the length of the string (including terminating NULL character) must be returned through the pDescriptionLength parameter.
• If both pszDescription and pDescriptionLength are not NULL, the driver must check the input value of pDescriptionLength to ensure that there's enough room in the allocated buffer, and then the length of the pszDescription string (including terminating NULL character) is passed out through the pDescriptionLength parameter.

Return value

If this routine succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code, including the following:

Remarks

This function should behave similarly to the CheckCounter function that supports Microsoft Direct3D 10 and later.

Counters are typically used by tools that capture a frame and play it back multiple times. The pass that records accurate timing info is separate from other passes. In later passes, a different set of counters is used each time. The priority should be to obtain an accurate correlation of counter results to draw calls, and the overhead incurred during playback can be sacrificed. The driver must insert flush calls or wait-for-idle calls to ensure an accurate correlation.

Typically an app can simultaneously monitor only a small number of possible native counters, which might number in the hundreds. Additionally, the driver must indicate the number of active counters used by monitoring each supported counter ID from the D3DDDIQUERYTYPE enumeration (both well-known counter IDs and device-specific counter IDs). For example, the driver can indicate that monitoring a FillRateUtilized variable requires 3 of the maximum 4 simultaneously active counters (indicated by the pActiveCounters parameter). The app can therefore also monitor another counter ID, as long as that counter ID requires one or fewer active counters.

If a counter ID can always be monitored (and it doesn't interfere with monitoring any other counter IDs), the number of simultaneous active counters required by the counter ID can be zero.

See also

CheckCounter

D3DDDIQUERYTYPE