84 lines
2.7 KiB
C#
84 lines
2.7 KiB
C#
///////////////////////////////////////////////////////////////////////////////
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//
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// Microsoft Research Singularity
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//
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//
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// Note:
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//
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namespace Microsoft.Singularity.Hal
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{
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using Microsoft.Singularity.Hal.Acpi;
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internal class Calibrate
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{
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private static uint PmDelta(uint newValue, uint oldValue)
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{
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// PmTimer may be 24 or 32 bits depending on system.
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// Simplest to treat as 24 bits.
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return (newValue - oldValue) & 0x00ffffff;
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}
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internal static void CpuCycleCounter(PMTimer pmTimer)
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{
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uint pmLast = pmTimer.Value;
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ulong tscLast = Processor.CycleCount;
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uint pmLimit = PMTimer.FrequencyHz / 15;
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uint pmAccum = 0;
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ulong tscNow = 0;
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// Initial measurements
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tscLast = Processor.CycleCount;
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pmLast = pmTimer.Value;
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// Measurement loop
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do
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{
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tscNow = Processor.CycleCount;
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uint pmNow = pmTimer.Value;
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pmAccum += PmDelta(pmNow, pmLast);
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pmLast = pmNow;
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} while (pmAccum < pmLimit);
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ulong tscHz = PMTimer.FrequencyHz * (tscNow - tscLast) / pmAccum;
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DebugStub.Print("Cpu{0}: TSC frequency {1} Hz\n",
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__arglist(Processor.CurrentProcessor.Id, tscHz));
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Processor.CyclesPerSecond = tscHz;
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}
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internal static void ApicTimer(PMTimer pmTimer, ApicTimer apicTimer)
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{
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apicTimer.SetDivisor(1);
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apicTimer.SetOneShot();
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apicTimer.SetInterruptEnabled(false);
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apicTimer.SetInitialCount(~0u);
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uint apicLast = apicTimer.Value;
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uint pmLast = pmTimer.Value;
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uint pmLimit = PMTimer.FrequencyHz / 15;
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uint pmAccum = 0;
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uint apicNow = 0;
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// Initial measurements
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apicLast = apicTimer.Value;
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pmLast = pmTimer.Value;
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do
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{
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apicNow = apicTimer.Value;
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uint pmNow = pmTimer.Value | 0xff000000;
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pmAccum += PmDelta(pmNow, pmLast);
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pmLast = pmNow;
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} while (pmAccum < pmLimit);
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ulong apicHz = PMTimer.FrequencyHz * (ulong)(apicLast - apicNow) / pmAccum;
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DebugStub.Print("Cpu{0}: APIC timer frequency {1} Hz\n",
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__arglist(Processor.CurrentProcessor.Id, apicHz));
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apicTimer.SetBusFrequency((uint)apicHz);
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}
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}
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}
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