--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/kernel/eka/memmodel/epoc/flexible/mmu/mthrash.cpp	Mon Oct 19 15:55:17 2009 +0100
@@ -0,0 +1,152 @@
+// Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies).
+// All rights reserved.
+// This component and the accompanying materials are made available
+// under the terms of the License "Eclipse Public License v1.0"
+// which accompanies this distribution, and is available
+// at the URL "http://www.eclipse.org/legal/epl-v10.html".
+//
+// Initial Contributors:
+// Nokia Corporation - initial contribution.
+//
+// Contributors:
+//
+// Description:
+// Other possible inputs to thrashing detection:
+// - cache size and free ram
+// - pin failures
+//
+
+
+
+#include <kernel/kern_priv.h>
+#include "mthrash.h"
+
+const TInt KUpdatePeriod = 1000;   // Update every second
+
+DThrashMonitor TheThrashMonitor;
+
+DThrashMonitor::DThrashMonitor() :
+	iRunning(EFalse),
+	iUpdateTimer(NULL, this),
+	iUpdateDfc(UpdateDfcFunc, this, 0),
+	iThrashLevel(0),
+	iThresholdThrashing(200),
+	iThresholdGood(150)
+	{
+	}
+
+void DThrashMonitor::Start()
+	{
+	TBool alreadyRunning = __e32_atomic_swp_ord32(&iRunning, ETrue);
+	if (alreadyRunning)
+		return;
+	
+	// reset
+	memclr(&iCount[0], sizeof(iCount));
+	iLastUpdateTime = NKern::TickCount();
+	
+	iUpdateDfc.SetDfcQ(Kern::DfcQue0());
+	TInt r = iUpdateTimer.OneShot(KUpdatePeriod, iUpdateDfc);
+	__NK_ASSERT_ALWAYS(r == KErrNone);
+	}
+
+TInt DThrashMonitor::ThrashLevel()
+	{
+	return iThrashLevel;
+	}
+
+TInt DThrashMonitor::SetThresholds(TUint aThrashing, TUint aGood)
+	{
+	if (aThrashing < aGood || aThrashing > 255)
+		return KErrArgument;
+	iThresholdThrashing = aThrashing;
+	iThresholdGood = aGood;
+	return KErrNone;
+	}
+
+void DThrashMonitor::UpdateCount(TCount aCount, TInt aDelta)
+	{
+	TCountData& c = iCount[aCount];
+
+	NKern::FMWait(&iMutex);
+	
+	TUint32 currentTime = NKern::TickCount();
+	c.iTotal += (TInt64)c.iCount * (currentTime - c.iLastUpdateTime);
+	c.iCount += aDelta;
+	c.iLastUpdateTime = currentTime;
+	
+	NKern::FMSignal(&iMutex);
+	
+	__NK_ASSERT_DEBUG(c.iCount >= 0);
+	}
+
+void DThrashMonitor::NotifyStartPaging()
+	{
+	UpdateCount(ECountThreadsPaging, 1);
+	}
+
+void DThrashMonitor::NotifyEndPaging()
+	{
+	UpdateCount(ECountThreadsPaging, -1);
+	}
+
+void DThrashMonitor::UpdateDfcFunc(TAny* aPtr)
+	{
+	DThrashMonitor* self = (DThrashMonitor*)aPtr;
+	self->RecalculateThrashLevel();
+	}
+
+void DThrashMonitor::RecalculateThrashLevel()
+	{
+	TInt currentTime = NKern::TickCount();
+	TInt elapsedTicks = currentTime - iLastUpdateTime;
+
+	NKern::FMWait(&iMutex);
+	for (TInt i = 0 ; i < EMaxCount ; ++i)
+		{
+		TCountData& c = iCount[i];
+		c.iTotal += (TInt64)c.iCount * (currentTime - c.iLastUpdateTime);
+		c.iAverage = (TInt)((256 * c.iTotal) / elapsedTicks);
+		c.iTotal = 0;
+		c.iLastUpdateTime = currentTime;
+		}
+	NKern::FMSignal(&iMutex);
+
+	TInt pagingActivity = Min(iCount[ECountThreadsPaging].iAverage, 255);
+
+	// Base thrash level entirely on the average number of threads paging
+	TInt newThrashLevel = pagingActivity;
+	TInt oldThrashLevel = iThrashLevel;
+
+	// Make thrash level increase slowly over time, but decrease quickly
+	if (newThrashLevel > oldThrashLevel)
+		newThrashLevel = (3 * oldThrashLevel + pagingActivity) >> 2;
+
+	iThrashLevel = newThrashLevel;
+	
+	// Notify user-side if thrashing thresholds passed
+	TBool notifyChange = EFalse;
+	if (oldThrashLevel < iThresholdThrashing && newThrashLevel >= iThresholdThrashing)
+		{
+		iIsThrashing = ETrue;
+		notifyChange = ETrue;
+		}
+	else if (iIsThrashing && oldThrashLevel >= iThresholdGood && newThrashLevel < iThresholdGood)
+		{
+		iIsThrashing = EFalse;
+		notifyChange = ETrue;
+		}
+	
+	if (notifyChange)
+		{
+		NKern::ThreadEnterCS();
+		Kern::AsyncNotifyChanges(EChangesThrashLevel);
+		NKern::ThreadLeaveCS();
+		}
+	
+	iLastUpdateTime = currentTime;
+	TInt r = iUpdateTimer.Again(KUpdatePeriod);
+	if (r == KErrArgument)
+		r = iUpdateTimer.OneShot(KUpdatePeriod, iUpdateDfc);
+	__NK_ASSERT_ALWAYS(r == KErrNone);
+	}