PerfQueryCounterInfo function (perflib.h)

Article
10/13/2021

Gets the counter specifications in the specified query.

Syntax

ULONG PerfQueryCounterInfo(
  [in]            HANDLE                   hQuery,
  [out, optional] PPERF_COUNTER_IDENTIFIER pCounters,
                  DWORD                    cbCounters,
  [out]           LPDWORD                  pcbCountersActual
);

Parameters

[in] hQuery

A handle to the query for which you want to get the counter specifications

[out, optional] pCounters

Pointer to a buffer that is large enough to hold the amount of data that the cbCounters parameter specifies, in bytes. May be NULL if cbCounters is 0.

cbCounters

The size of the pCounters buffer, in bytes.

[out] pcbCountersActual

The size of the buffer actually required to get the counter specifications. The meaning depends on the value that the function

returns.

Function Return Value	Meaning of pcbCountersActual
ERROR_SUCCESS	The number of bytes of information about the counter specifications that the function stored in the buffer that pCounters specified.
ERROR_NOT_ENOUGH_MEMORY	The size of the buffer required to store the information about the counter specifications, in bytes. Enlarge the buffer to the required size and call the function again.
Other	The value is undefined and should not be used.

Function Return Value

Meaning of pcbCountersActual

ERROR_SUCCESS

The number of

bytes of information about the counter specifications that the function stored in the buffer that pCounters specified.

ERROR_NOT_ENOUGH_MEMORY

The

size of the buffer required to store the information about the counter specifications, in bytes. Enlarge the buffer to the required

size and call the function again.

Other

The value is undefined and should not be used.

Return value

Return code	Description
ERROR_SUCCESS	The function successfully stored all of the information about the counter specifications in the buffer that pCounters specified. The value that pcbCountersActual points to indicates amount of information actually stored in the buffer, in bytes.
ERROR_NOT_ENOUGH_MEMORY	The buffer that pCounters specified was not large enough to store all of the information about the counter specifications. The value that pcbCountersActual points to indicates the size of the buffer required to store all of the information. Enlarge the buffer to the required size and call the function again.

For other types of failures, the return value is a system error code.

Remarks

The information about the counter specifications is written to the buffer that pCounters specifies as a sequence of PERF_COUNTER_IDENTIFIER blocks. The size in bytes of

the sequence of blocks is written to pcbCountersActual. Each PERF_COUNTER_IDENTIFIER block consists

of a PERF_COUNTER_IDENTIFIER structure, optionally followed by a null-terminated UTF-16LE

instance name, followed by padding so that the size of the

PERF_COUNTER_IDENTIFIER block is a multiple of 8 bytes. The size of each block, including the PERF_COUNTER_IDENTIFIER structure, instance name, and padding, is determined by the Size member of the PERF_COUNTER_IDENTIFIER structure, which will be a multiple of 8 bytes.

Requirements

Requirement	Value
Minimum supported client	Windows 10, version 1607 [desktop apps only]
Minimum supported server	Windows Server 2016 [desktop apps only]
Target Platform	Windows
Header	perflib.h
Library	AdvAPI32.lib
DLL	AdvAPI32.dll