Differential D2726 Diff 11884 source/lib/sysdep/os/win/whrt/tsc.cpp

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source/lib/sysdep/os/win/whrt/tsc.cpp

/* Copyright (C) 2010 Wildfire Games.		/* Copyright (C) 2020 Wildfire Games.
*		*
* Permission is hereby granted, free of charge, to any person obtaining		* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the		* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including		* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,		* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to		* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to		* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:		* the following conditions:
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#include "lib/sysdep/acpi.h"		#include "lib/sysdep/acpi.h"
#include "lib/sysdep/os_cpu.h"		#include "lib/sysdep/os_cpu.h"
#include "lib/sysdep/os/win/win.h"		#include "lib/sysdep/os/win/win.h"
#include "lib/sysdep/os/win/wutil.h"		#include "lib/sysdep/os/win/wutil.h"

#if ARCH_X86_X64		#if ARCH_X86_X64
# include "lib/sysdep/arch/x86_x64/x86_x64.h" // x86_x64::rdtsc		# include "lib/sysdep/arch/x86_x64/x86_x64.h" // x86_x64::rdtsc
# include "lib/sysdep/arch/x86_x64/topology.h"		# include "lib/sysdep/arch/x86_x64/topology.h"
# include "lib/sysdep/arch/x86_x64/msr.h"
#endif		#endif


//-----------------------------------------------------------------------------		//-----------------------------------------------------------------------------

static bool IsUniprocessor()		static bool IsUniprocessor()
{		{
if(topology::NumPackages() != 1)		if(topology::NumPackages() != 1)
▲ Show 20 Lines • Show All 132 Lines • ▼ Show 20 Lines	if(fadt)
if(fadt->IsC3Supported())		if(fadt->IsC3Supported())
return false;		return false;

// frequency throttling possible => unsafe.		// frequency throttling possible => unsafe.
if(fadt->IsDutyCycleSupported())		if(fadt->IsDutyCycleSupported())
return false;		return false;
}		}

#if ARCH_X86_X64
// recent CPU:
//if(x86_x64::Generation() >= 7)
{
// note: 8th generation CPUs support C1-clock ramping, which causes
// drift on multi-core systems, but those were excluded above.

// in addition to frequency changes due to P-state transitions,
// we're also subject to STPCLK throttling. this happens when
// the chipset thinks the system is dangerously overheated; the
// OS isn't even notified. this may be rare, but could cause
// incorrect results => unsafe.
//return false;
}
#endif

// we're dealing with a single older CPU; the only problem there is		// we're dealing with a single older CPU; the only problem there is
// throttling, i.e. changes to the TSC frequency. we don't want to		// throttling, i.e. changes to the TSC frequency. we don't want to
// disable this because it may be important for cooling. the OS		// disable this because it may be important for cooling. the OS
// initiates changes but doesn't notify us; jumps are too frequent		// initiates changes but doesn't notify us; jumps are too frequent
// and drastic to detect and account for => unsafe.		// and drastic to detect and account for => unsafe.
if(IsThrottlingPossible())		if(IsThrottlingPossible())
return false;		return false;

return true;		return true;
}		}

u64 Counter() const		u64 Counter() const
{		{
return x86_x64::rdtsc();		return x86_x64::rdtsc();
}		}

size_t CounterBits() const		size_t CounterBits() const
{		{
return 64;		return 64;
}		}

double NominalFrequency() const		double NominalFrequency() const
{		{
// WARNING: do not call x86_x64::ClockFrequency because it uses the
// HRT, which we're currently in the process of initializing.
// instead query CPU clock frequency via OS.
//
// note: even here, initial accuracy isn't critical because the
// clock is subject to thermal drift and would require continual
// recalibration anyway.
#if ARCH_X86_X64
if(MSR::IsAccessible() && MSR::HasPlatformInfo())
{
const i64 busFrequency = IsSandyBridge()? 100000000 : 133333333;
const u64 platformInfo = MSR::Read(MSR::PLATFORM_INFO);
const u8 maxNonTurboRatio = bits(platformInfo, 8, 15);
return double(maxNonTurboRatio) * busFrequency;
}
else
#endif
return os_cpu_ClockFrequency();		return os_cpu_ClockFrequency();
}		}

double Resolution() const		double Resolution() const
{		{
return 1.0 / NominalFrequency();		return 1.0 / NominalFrequency();
}		}
};		};

ICounter* CreateCounterTSC(void* address, size_t size)		ICounter* CreateCounterTSC(void* address, size_t size)
{		{
ENSURE(sizeof(CounterTSC) <= size);		ENSURE(sizeof(CounterTSC) <= size);
return new(address) CounterTSC();		return new(address) CounterTSC();
}		}