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tier0/cpu_usage.cpp

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+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: return the cpu usage as a float value
+//
+// On win32 this is 0.0 to 1.0 indicating the amount of CPU time used
+// On posix its the load avg from the last minute
+// 
+// On win32 you need to call this once in a while.  Every few seconds.
+// First call returns zero
+//=============================================================================//
+
+#include "pch_tier0.h"
+#include "tier0/platform.h"
+
+#ifdef WIN32
+
+#include <windows.h>
+
+#define SystemBasicInformation 0
+#define SystemPerformanceInformation 2
+#define SystemTimeInformation 3
+
+#define Li2Double(x) ((double)((x).HighPart) * 4.294967296E9 + (double)((x).LowPart))
+
+typedef struct
+{
+	DWORD dwUnknown1;
+	ULONG uKeMaximumIncrement;
+	ULONG uPageSize;
+	ULONG uMmNumberOfPhysicalPages;
+	ULONG uMmLowestPhysicalPage;
+	ULONG uMmHighestPhysicalPage;
+	ULONG uAllocationGranularity;
+	PVOID pLowestUserAddress;
+	PVOID pMmHighestUserAddress;
+	ULONG uKeActiveProcessors;
+	BYTE bKeNumberProcessors;
+	BYTE bUnknown2;
+	WORD wUnknown3;
+} SYSTEM_BASIC_INFORMATION;
+
+typedef struct
+{
+	LARGE_INTEGER liIdleTime;
+	DWORD dwSpare[80];
+} SYSTEM_PERFORMANCE_INFORMATION;
+
+typedef struct
+{
+	LARGE_INTEGER liKeBootTime;
+	LARGE_INTEGER liKeSystemTime;
+	LARGE_INTEGER liExpTimeZoneBias;
+	ULONG uCurrentTimeZoneId;
+	DWORD dwReserved;
+} SYSTEM_TIME_INFORMATION;
+
+typedef LONG (WINAPI *PROCNTQSI)(UINT,PVOID,ULONG,PULONG);
+
+static PROCNTQSI NtQuerySystemInformation;
+
+float GetCPUUsage() 
+{
+	SYSTEM_PERFORMANCE_INFORMATION SysPerfInfo;
+	SYSTEM_TIME_INFORMATION SysTimeInfo;
+	SYSTEM_BASIC_INFORMATION SysBaseInfo;
+	double dbIdleTime;
+	double dbSystemTime;
+	LONG status;
+	static LARGE_INTEGER liOldIdleTime = {0,0};
+	static LARGE_INTEGER liOldSystemTime = {0,0};
+
+	if ( !NtQuerySystemInformation)
+	{
+		NtQuerySystemInformation = (PROCNTQSI)GetProcAddress( GetModuleHandle("ntdll"), "NtQuerySystemInformation" );
+
+		if ( !NtQuerySystemInformation )
+			return(0);
+	}
+
+	// get number of processors in the system
+	status = NtQuerySystemInformation( SystemBasicInformation,&SysBaseInfo,sizeof(SysBaseInfo),NULL );
+	if ( status != NO_ERROR )
+		return(0);
+
+	// get new system time
+	status = NtQuerySystemInformation( SystemTimeInformation,&SysTimeInfo,sizeof(SysTimeInfo),0 );
+	if ( status!=NO_ERROR )
+		return(0);
+
+	// get new CPU's idle time
+	status = NtQuerySystemInformation( SystemPerformanceInformation,&SysPerfInfo,sizeof(SysPerfInfo),NULL );
+	if ( status != NO_ERROR )
+		return(0);
+
+	// if it's a first call - skip it
+	if ( liOldIdleTime.QuadPart != 0 )
+	{
+		// CurrentValue = NewValue - OldValue
+		dbIdleTime = Li2Double(SysPerfInfo.liIdleTime) - Li2Double(liOldIdleTime);
+		dbSystemTime = Li2Double(SysTimeInfo.liKeSystemTime) - Li2Double(liOldSystemTime);
+
+		// CurrentCpuIdle = IdleTime / SystemTime
+		dbIdleTime = dbIdleTime / dbSystemTime / (double)SysBaseInfo.bKeNumberProcessors;
+
+		// CurrentCpuUsage% = 100 - (CurrentCpuIdle * 100) / NumberOfProcessors
+		// dbIdleTime = 100.0 - dbIdleTime * 100.0 / (double)SysBaseInfo.bKeNumberProcessors + 0.5;
+	}
+	else
+	{
+		dbIdleTime = 1.0f;
+	}
+
+	// store new CPU's idle and system time
+	liOldIdleTime = SysPerfInfo.liIdleTime;
+	liOldSystemTime = SysTimeInfo.liKeSystemTime;
+
+	return (float)(1.0f - dbIdleTime);
+}
+
+#endif // WIN32
+
+#ifdef POSIX
+#include <stdlib.h>
+
+float GetCPUUsage() 
+{
+	double loadavg[3];
+
+	getloadavg( loadavg, 3 );
+	return loadavg[0];
+}
+#endif //POSIX