PERF_DATA_HEADER structure (perflib.h)
Provides information about the PERF_DATA_HEADER block that contains the structure. A PERF_DATA_HEADER block corresponds to one query specification in a query, and consists of a PERF_DATA_HEADER structure followed by a sequence of PERF_COUNTER_HEADER blocks.
Syntax
typedef struct _PERF_DATA_HEADER {
ULONG dwTotalSize;
ULONG dwNumCounters;
LONGLONG PerfTimeStamp;
LONGLONG PerfTime100NSec;
LONGLONG PerfFreq;
SYSTEMTIME SystemTime;
} PERF_DATA_HEADER, *PPERF_DATA_HEADER;
Members
dwTotalSize
The sum of the size of the PERF_DATA_HEADER structure and the sizes of all of the PERF_COUNTER_HEADER blocks in the PERF_DATA_HEADER block.
dwNumCounters
The number of PERF_COUNTER_HEADER blocks that the PERF_DATA_HEADER block contains.
PerfTimeStamp
The timestamp from a high-resolution clock.
PerfTime100NSec
The number of 100 nanosecond intervals since January 1, 1601, in Coordinated Universal Time (UTC).
PerfFreq
The frequency of a high-resolution clock.
SystemTime
The time at which data is collected by the provider.
Remarks
The ordering of the PERF_COUNTER_HEADER blocks is based on the Index member of the PERF_COUNTER_IDENTIFIER blocks that the PerfQueryCounterInfo function gets. Each PERF_COUNTER_HEADER block is 8-byte aligned, so the value of the dwTotalSize is a multiple of 8 bytes.
The timestamp information in the PERF_DATA_HEADER structure is required when you compute the display values of certain performance counters.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 10, version 1607 [desktop apps only] |
| Minimum supported server | Windows Server 2016 [desktop apps only] |
| Header | perflib.h |