SYSTEM_CONTEXT_SWITCH_INFORMATION

The SYSTEM_CONTEXT_SWITCH_INFORMATION structure is what a successful call to ZwQuerySystemInformation or NtQuerySystemInformation produces in its output buffer when given the information class SystemContextSwitchInformation (0x24).

Documentation Status

The SYSTEM_CONTEXT_SWITCH_INFORMATION structure is not documented.

Microsoft does publish the practical equivalent of a C-language definition as type information in public symbol files, though not for the kernel, where the structure is prepared, nor even for low-level user-mode DLLs that interpret the structure, but for various higher-level user-mode DLLs such as URLMON.DLL and only then starting with version 6.2.

Two earlier disclosures of type information are known, though not in symbol files but in statically linked libraries: GDISRVL.LIB from the Device Driver Kit (DDK) for Windows NT 3.51; and SHELL32.LIB from the DDK for Windows NT 4.0.

Layout

The SYSTEM_CONTEXT_SWITCH_INFORMATION is 0x30 bytes in both 32-bit and 64-bit Windows, respectively, in version 4.0 and higher. It is originally 0x28 bytes.

ULONG ContextSwitches;

ULONG FindAny;

ULONG FindLast;

ULONG FindIdeal;

ULONG IdleAny;

ULONG IdleCurrent;

ULONG IdleLast;

ULONG IdleIdeal;

ULONG PreemptAny;

ULONG PreemptCurrent;

ULONG PreemptLast;

ULONG SwitchToIdle;