public class SwapFile {
public static OpenFile swapFile;
private static String swapName;
private static int PAGESIZE = Machine.processor().pageSize;
public static List<Integer> freePages;
public static List<Integer> allocatedPages;
private static Lock swapLock;
private static byte[] memory = Machine.processor().getMemory();
public static void initialize(String filename) {
swapFile = ThreadedKernel.fileSystem.open(filename, true);
swapName = filename;
freePages = new LinkedList<Integer>();
allocatedPages = new LinkedList<Integer>();
swapLock = new Lock();
}
public static void close() {
swapFile.close();
ThreadedKernel.fileSystem.remove(swapName);
}
public static int insertPage(int spn, int ppn) {
swapLock.acquire();
int numBits = swapFile.write(spn * PAGESIZE, memory, ppn * PAGESIZE, PAGESIZE);
// assert that numBits == PAGESIZE
allocatedPages.add(spn);
swapLock.release();
return spn;
}
/* we will try to allocate a free page from the freepages*/
public static int insertPage(int ppn) {
int numBits = 0;
int spn = swapFile.length() / PAGESIZE;
if (freePages.size() > 0) {
spn = freePages.remove(0);
}
return insertPage(spn, ppn);
}
public static void readPage(int spn, int ppn) {
if (allocatedPages.contains(spn)) {
swapLock.acquire();
swapFile.read(spn * PAGESIZE, memory, ppn * PAGESIZE, PAGESIZE);
swapLock.release();
} else {
}
}
public static void free(int page) {
swapLock.acquire();
freePages.add(page);
swapLock.release();
}
}
/**
* Initialize this kernel. Creates a synchronized console and sets the
* processor's exception handler.
*/
public void initialize(String[] args) {
super.initialize(args);
console = new SynchConsole(Machine.console());
Machine.processor().setExceptionHandler(new Runnable() {
public void run() { exceptionHandler(); }
});
}
private void syncTLB() {
for (int i = 0; i < Machine.processor().getTLBSize(); i++) {
TranslationEntry tE = Machine.processor().readTLBEntry(i);
if (tE.valid) {
pageTable[tE.vpn].dirty = tE.dirty;
pageTable[tE.vpn].used = tE.used;
}
}
}
/**
* Save the state of this process in preparation for a context switch. Called by
* <tt>UThread.saveState()</tt>.
*/
public void saveState() {
for (int i = 0; i < Machine.processor().getTLBSize(); i++) {
TranslationEntry tE = Machine.processor().readTLBEntry(i);
if (tE.valid) {
pageTable[tE.vpn].dirty = tE.dirty;
pageTable[tE.vpn].used = tE.used;
}
tE.valid = false;
Machine.processor().writeTLBEntry(i, tE);
// savedState[i] = tE.vpn;
}
}
/**
* The exception handler. This handler is called by the processor whenever
* a user instruction causes a processor exception.
*
* <p>
* When the exception handler is invoked, interrupts are enabled, and the
* processor's cause register contains an integer identifying the cause of
* the exception (see the <tt>exceptionZZZ</tt> constants in the
* <tt>Processor</tt> class). If the exception involves a bad virtual
* address (e.g. page fault, TLB miss, read-only, bus error, or address
* error), the processor's BadVAddr register identifies the virtual address
* that caused the exception.
*/
public void exceptionHandler() {
Lib.assert(KThread.currentThread() instanceof UThread);
UserProcess process = ((UThread) KThread.currentThread()).process;
int cause = Machine.processor().readRegister(Processor.regCause);
process.handleException(cause);
}
/**
* Transfer data from the specified array to this process's virtual memory. This method handles
* address translation details. This method must <i>not</i> destroy the current process if an
* error occurs, but instead should return the number of bytes successfully copied (or zero if no
* data could be copied).
*
* @param vaddr the first byte of virtual memory to write.
* @param data the array containing the data to transfer.
* @param offset the first byte to transfer from the array.
* @param length the number of bytes to transfer from the array to virtual memory.
* @return the number of bytes successfully transferred.
*/
public int writeVirtualMemory(int vaddr, byte[] data, int offset, int length) {
Lib.assertTrue(offset >= 0 && length >= 0 && offset + length <= data.length);
byte[] memory = Machine.processor().getMemory();
int transferred = 0;
while (length > 0 && offset < data.length) {
int addrOffset = vaddr % 1024;
int virtualPage = vaddr / 1024;
if (virtualPage >= pageTable.length || virtualPage < 0) {
break;
}
TranslationEntry pte = pageTable[virtualPage];
if (!pte.valid || pte.readOnly) {
break;
}
pte.used = true;
pte.dirty = true;
int physPage = pte.ppn;
int physAddr = physPage * 1024 + addrOffset;
int transferLength = Math.min(data.length - offset, Math.min(length, 1024 - addrOffset));
System.arraycopy(data, offset, memory, physAddr, transferLength);
vaddr += transferLength;
offset += transferLength;
length -= transferLength;
transferred += transferLength;
}
return transferred;
}
/** Handle the halt() system call. */
private int handleHalt() {
if (this.process_id != ROOT) {
return 0;
}
Machine.halt();
Lib.assertNotReached("Machine.halt() did not halt machine!");
return 0;
}
/**
* Start running user programs, by creating a process and running a shell
* program in it. The name of the shell program it must run is returned by
* <tt>Machine.getShellProgramName()</tt>.
*
* @see nachos.machine.Machine#getShellProgramName
*/
public void run() {
super.run();
UserProcess process = UserProcess.newUserProcess();
String shellProgram = Machine.getShellProgramName();
Lib.assert(process.execute(shellProgram, new String[] { }));
KThread.currentThread().finish();
}
/**
* Handle a user exception. Called by <tt>UserKernel.exceptionHandler()</tt> . The <i>cause</i>
* argument identifies which exception occurred; see the <tt>Processor.exceptionZZZ</tt>
* constants.
*
* @param cause the user exception that occurred.
*/
public void handleException(int cause) {
Processor processor = Machine.processor();
switch (cause) {
case Processor.exceptionTLBMiss:
handleTLBMiss();
break;
default:
super.handleException(cause);
break;
}
}
/**
* Initialize the processor's registers in preparation for running the program loaded into this
* process. Set the PC register to point at the start function, set the stack pointer register to
* point at the top of the stack, set the A0 and A1 registers to argc and argv, respectively, and
* initialize all other registers to 0.
*/
public void initRegisters() {
Processor processor = Machine.processor();
// by default, everything's 0
for (int i = 0; i < processor.numUserRegisters; i++) processor.writeRegister(i, 0);
// initialize PC and SP according
processor.writeRegister(Processor.regPC, initialPC);
processor.writeRegister(Processor.regSP, initialSP);
// initialize the first two argument registers to argc and argv
processor.writeRegister(Processor.regA0, argc);
processor.writeRegister(Processor.regA1, argv);
}
/**
* Allocates memory for this process, and loads the COFF sections into memory. If this returns
* successfully, the process will definitely be run (this is the last step in process
* initialization that can fail).
*
* @return <tt>true</tt> if the sections were successfully loaded.
*/
protected boolean loadSections() {
if (numPages > Machine.processor().getNumPhysPages()) {
coff.close();
Lib.debug(dbgProcess, "\tinsufficient physical memory");
return false;
}
pageTable = new TranslationEntry[numPages];
for (int i = 0; i < numPages; i++) {
int physPage = UserKernel.allocatePage();
if (physPage < 0) {
Lib.debug(dbgProcess, "\tunable to allocate pages; tried " + numPages + ", did " + i);
for (int j = 0; j < i; j++) {
if (pageTable[j].valid) {
UserKernel.deallocatePage(pageTable[j].ppn);
pageTable[j].valid = false;
}
}
coff.close();
return false;
}
pageTable[i] = new TranslationEntry(i, physPage, true, false, false, false);
}
// load sections
for (int s = 0; s < coff.getNumSections(); s++) {
CoffSection section = coff.getSection(s);
Lib.debug(
dbgProcess,
"\tinitializing " + section.getName() + " section (" + section.getLength() + " pages)");
for (int i = 0; i < section.getLength(); i++) {
int vpn = section.getFirstVPN() + i;
// for now, just assume virtual addresses=physical addresses
int ppn = pageTable[vpn].ppn;
section.loadPage(i, ppn);
if (section.isReadOnly()) {
pageTable[vpn].readOnly = true;
}
}
}
coff.close();
return true;
}
/** Allocate a new process. */
public UserProcess() {
map = new HashMap<Integer, childProcess>();
int numPhysPages = Machine.processor().getNumPhysPages();
pageTable = new TranslationEntry[numPhysPages];
for (int i = 0; i < numPhysPages; i++)
pageTable[i] = new TranslationEntry(i, i, true, false, false, false);
this.process_id = unique;
unique++;
openfiles = new HashMap<Integer, OpenFile>();
available_descriptors =
new ArrayList<Integer>(Arrays.asList(2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15));
openfiles.put(0, UserKernel.console.openForReading());
openfiles.put(1, UserKernel.console.openForWriting());
}
/**
* Start this autograder. Extract the <tt>-#</tt> arguments, call <tt>init()</tt>, load and
* initialize the kernel, and call <tt>run()</tt>.
*
* @param privilege encapsulates privileged access to the Nachos machine.
*/
public void start(Privilege privilege) {
Lib.assertTrue(this.privilege == null, "start() called multiple times");
this.privilege = privilege;
String[] args = Machine.getCommandLineArguments();
extractArguments(args);
System.out.print(" grader");
init();
System.out.print("\n");
kernel = (Kernel) Lib.constructObject(Config.getString("Kernel.kernel"));
kernel.initialize(args);
run();
}
/**
* Handle a user exception. Called by <tt>UserKernel.exceptionHandler()</tt>. The <i>cause</i>
* argument identifies which exception occurred; see the <tt>Processor.exceptionZZZ</tt>
* constants.
*
* @param cause the user exception that occurred.
*/
public void handleException(int cause) {
Processor processor = Machine.processor();
switch (cause) {
case Processor.exceptionSyscall:
int result =
handleSyscall(
processor.readRegister(Processor.regV0),
processor.readRegister(Processor.regA0),
processor.readRegister(Processor.regA1),
processor.readRegister(Processor.regA2),
processor.readRegister(Processor.regA3));
processor.writeRegister(Processor.regV0, result);
processor.advancePC();
break;
default:
Lib.debug(dbgProcess, "Unexpected exception: " + Processor.exceptionNames[cause]);
handleExit(-1);
Lib.assertNotReached("Unexpected exception");
}
}
/**
* Allocate and return a new process of the correct class. The class name is specified by the
* <tt>nachos.conf</tt> key <tt>Kernel.processClassName</tt>.
*
* @return a new process of the correct class.
*/
public static UserProcess newUserProcess() {
return (UserProcess) Lib.constructObject(Machine.getProcessClassName());
}
private void delay() {
long time = Machine.timer().getTime();
int amount = 1000;
ThreadedKernel.alarm.waitUntil(amount);
Lib.my_assert(Machine.timer().getTime() >= time + amount);
}
private void allocatePage(int vpn) {
// System.out.println("TLBMiss: VPN:" + vpn + " of Process " + processID);
TranslationEntry t = pageTable[vpn];
if (!t.valid) {
// System.out.println("Allocating VPN: " + t.vpn);
lock.acquire();
if (UserKernel.freePages.size() > 0) {
int ppn = ((Integer) UserKernel.freePages.removeFirst()).intValue();
t.valid = true;
if (!t.dirty) {
t.ppn = ppn;
IPT[ppn] = new IPTEntry();
IPT[ppn].process = this;
IPT[ppn].tE = t;
boolean isCoffSection = false;
for (int s = 0; s < coff.getNumSections(); s++) {
if (isCoffSection) {
break;
}
CoffSection section = coff.getSection(s);
if (section.getFirstVPN() > t.vpn) {
continue;
}
for (int i = 0; i < section.getLength(); i++) {
int svpn = section.getFirstVPN() + i;
if (svpn == t.vpn) {
section.loadPage(i, pinVirtualPage(t.vpn, false));
// System.out.println("VPN \"" + t.vpn + "\" is a COFF section");
// System.out.println("COFF section loaded into VPN \"" + t.vpn + "\" PPN \"" +
// t.ppn + "\"");
isCoffSection = true;
break;
}
}
}
if (!isCoffSection) {
// System.out.println("VPN \"" + t.vpn + "\" is NOT a COFF section");
// System.out.println("PPN \"" + t.ppn + "\" Zero'd Out");
byte[] data = new byte[Processor.pageSize];
// writeVirtualMemory(t.vpn, data, 0, Processor.pageSize);
byte[] memory = Machine.processor().getMemory();
System.arraycopy(data, 0, memory, t.ppn * Processor.pageSize, Processor.pageSize);
}
} else // Dirty
{
// System.out.println("VPN \"" + t.vpn + "\" has been swapped out, swaping into
// PPN \"" + ppn + "\"");
int spn = t.ppn;
byte[] data = new byte[pageSize];
byte[] memory = Machine.processor().getMemory();
OpenFile swap = ThreadedKernel.fileSystem.open(".Nachos.swp", false);
swap.read(spn * pageSize, memory, ppn * pageSize, pageSize);
swap.close();
t.ppn = ppn;
// System.out.println(spn);
freeSwapPages.set(spn, true);
IPT[ppn] = new IPTEntry();
IPT[ppn].process = this;
IPT[ppn].tE = t;
// System.out.println("SPN \"" + spn + "\" has been swapped in.");
}
} else {
syncTLB();
// Clock Algorithm
unpinnedPageLock.acquire();
int numPinnedPages = 0;
while (IPT[victim] == null || IPT[victim].tE.used || IPT[victim].pinCount) {
if (IPT[victim] != null) {
IPT[victim].tE.used = false;
// System.out.println("PPN " + victim + " is used.");
}
if (IPT[victim].pinCount) {
numPinnedPages++;
// System.out.println("PPN " + victim + " is pinned.");
}
if (numPinnedPages == IPT.length) unpinnedPage.sleep();
// System.out.println("This Process is " + this.processID + " and the IPT's
// process is " + IPT[victim].processID);
victim = (victim + 1) % Machine.processor().getNumPhysPages();
}
// System.out.println("PPN " + victim + " will be evicted.");
unpinnedPageLock.release();
int evict = IPT[victim].tE.vpn;
VMProcess evictedOwner = IPT[victim].process;
int evictedPPN = victim;
victim = (victim + 1) % Machine.processor().getNumPhysPages();
// System.out.println("Not enough pysical memory, evicting VPN \"" + evict + "\" of process
// " + evictedOwner.processID);
// Swap Files
if (evictedOwner.isDirty(evict)) {
// System.out.println("VPN \"" + evict + "\" is dirty, swapping out.");
OpenFile swap = ThreadedKernel.fileSystem.open(".Nachos.swp", false);
int spn = 0;
for (spn = 0; spn < freeSwapPages.size(); spn++) {
if (freeSwapPages.get(spn)) {
break;
}
}
if (spn == freeSwapPages.size()) {
freeSwapPages.add(false);
} else {
freeSwapPages.set(spn, false);
}
UserKernel.freePages.add(evictedPPN);
byte[] memory = Machine.processor().getMemory();
swap.write(spn * pageSize, memory, evictedPPN * pageSize, pageSize);
swap.close();
if (evictedOwner.processID != this.processID) {
evictedOwner.evict(evict, spn);
} else {
pageTable[evict].ppn = spn;
pageTable[evict].valid = false;
}
for (int i = 0; i < Machine.processor().getTLBSize(); i++) {
TranslationEntry tE = Machine.processor().readTLBEntry(i);
if (tE.vpn == evict && tE.ppn == evictedPPN) {
// System.out.println("TLBEntry " + i + " invalid");
tE.valid = false;
Machine.processor().writeTLBEntry(i, tE);
}
}
lock.release();
// System.out.println("VPN \"" + evict + "\" of Process " + this.processID + "
// swapped out to SPN \"" + spn + "\".");
// Machine.processor().readTLBEntry(evict).valid = false;
allocatePage(vpn);
return;
} else {
if (evictedOwner.processID != this.processID) {
// System.out.println("Evicted VPN " + evict + " of Process " + this.processID);
evictedOwner.evict(evict);
} else {
pageTable[evict].valid = false;
}
UserKernel.freePages.add(evictedPPN);
for (int i = 0; i < Machine.processor().getTLBSize(); i++) {
TranslationEntry tE = Machine.processor().readTLBEntry(i);
if (tE.vpn == evict && tE.ppn == evictedPPN) {
// System.out.println("TLBEntry " + i + " invalid");
tE.valid = false;
Machine.processor().writeTLBEntry(i, tE);
}
}
lock.release();
allocatePage(vpn);
return;
}
}
lock.release();
}
for (int i = 0; i < Machine.processor().getTLBSize(); i++) {
TranslationEntry tE = Machine.processor().readTLBEntry(i);
if (!tE.valid) {
// System.out.println("Evicted TLBEntry " + i);
Machine.processor().writeTLBEntry(i, t);
// System.out.println(t.valid);
return;
}
}
syncTLB();
int evictedEntry = (int) (Math.random() * Machine.processor().getTLBSize());
TranslationEntry tE = Machine.processor().readTLBEntry(evictedEntry);
pageTable[tE.vpn] = tE;
Machine.processor().writeTLBEntry(evictedEntry, t);
// System.out.println("Evicted TLBEntry " + evictedEntry + " randomly");
// System.out.println("TE entered is VPN \"" + t.vpn + "\" PPN \"" + t.ppn + "\"");
}
public void handleTLBMiss() {
int vaddr = Machine.processor().readRegister(Processor.regBadVAddr);
int vpn = Processor.pageFromAddress(vaddr);
allocatePage(vpn);
}
/**
* Restore the state of this process after a context switch. Called by
* <tt>UThread.restoreState()</tt>.
*/
public void restoreState() {
Machine.processor().setPageTable(pageTable);
}
/** A <tt>UserProcess</tt> that supports demand-paging. */
public class VMProcess extends UserProcess {
/** Allocate a new process. */
public VMProcess() {
super();
}
/**
* Save the state of this process in preparation for a context switch. Called by
* <tt>UThread.saveState()</tt>.
*/
public void saveState() {
for (int i = 0; i < Machine.processor().getTLBSize(); i++) {
TranslationEntry tE = Machine.processor().readTLBEntry(i);
if (tE.valid) {
pageTable[tE.vpn].dirty = tE.dirty;
pageTable[tE.vpn].used = tE.used;
}
tE.valid = false;
Machine.processor().writeTLBEntry(i, tE);
// savedState[i] = tE.vpn;
}
}
/**
* Restore the state of this process after a context switch. Called by
* <tt>UThread.restoreState()</tt>.
*/
public void restoreState() {
/*for(int i = 0; i < Machine.processor().getTLBSize(); i++)
{
TranslationEntry tE = Machine.processor().readTLBEntry(i);
tE.valid = false;
Machine.processor().writeTLBEntry(i, tE);
}
for(int i = 0; i < Machine.processor().getTLBSize(); i++)
{
if(pageTable[savedState[i]].valid)
{
Machine.processor().writeTLBEntry(i, pageTable[savedState[i]]);
}
}*/
}
/**
* Initializes page tables for this process so that the executable can be demand-paged.
*
* @return <tt>true</tt> if successful.
*/
protected boolean loadSections() {
UserKernel.memoryLock.acquire();
pageTable = new TranslationEntry[numPages];
for (int vpn = 0; vpn < numPages; vpn++) {
pageTable[vpn] = new TranslationEntry(vpn, -1, false, false, false, false);
}
UserKernel.memoryLock.release();
// load sections
for (int s = 0; s < coff.getNumSections(); s++) {
CoffSection section = coff.getSection(s);
Lib.debug(
dbgProcess,
"\tinitializing " + section.getName() + " section (" + section.getLength() + " pages)");
for (int i = 0; i < section.getLength(); i++) {
int vpn = section.getFirstVPN() + i;
pageTable[vpn].readOnly = section.isReadOnly();
// section.loadPage(i, pinVirtualPage(vpn, false));
}
}
return true;
}
/** Release any resources allocated by <tt>loadSections()</tt>. */
protected void unloadSections() {
for (int vpn = 0; vpn < pageTable.length; vpn++) {
if (pageTable[vpn].valid) {
UserKernel.freePages.add(new Integer(pageTable[vpn].ppn));
// IPT[pageTable[vpn].ppn] = null;
}
}
}
/**
* Handle a user exception. Called by <tt>UserKernel.exceptionHandler()</tt> . The <i>cause</i>
* argument identifies which exception occurred; see the <tt>Processor.exceptionZZZ</tt>
* constants.
*
* @param cause the user exception that occurred.
*/
public void handleException(int cause) {
Processor processor = Machine.processor();
switch (cause) {
case Processor.exceptionTLBMiss:
handleTLBMiss();
break;
default:
super.handleException(cause);
break;
}
}
protected int pinVirtualPage(int vpn, boolean isUserWrite) {
int ppn = super.pinVirtualPage(vpn, isUserWrite);
if (ppn >= 0) {
if (isUserWrite) {
IPT[ppn].pinCount = true;
}
} else {
if (vpn < 0 || vpn >= pageTable.length) return -1;
if (!pageTable[vpn].valid) {
allocatePage(vpn);
}
ppn = super.pinVirtualPage(vpn, isUserWrite);
if (isUserWrite) {
IPT[ppn].pinCount = true;
}
}
return ppn;
}
protected void unpinVirtualPage(int vpn) {
int ppn = super.pinVirtualPage(vpn, false);
if (ppn >= 0) {
IPT[ppn].pinCount = false;
unpinnedPageLock.acquire();
unpinnedPage.wake();
unpinnedPageLock.release();
}
}
public void handleTLBMiss() {
int vaddr = Machine.processor().readRegister(Processor.regBadVAddr);
int vpn = Processor.pageFromAddress(vaddr);
allocatePage(vpn);
}
private void syncTLB() {
for (int i = 0; i < Machine.processor().getTLBSize(); i++) {
TranslationEntry tE = Machine.processor().readTLBEntry(i);
if (tE.valid) {
pageTable[tE.vpn].dirty = tE.dirty;
pageTable[tE.vpn].used = tE.used;
}
}
}
private void allocatePage(int vpn) {
// System.out.println("TLBMiss: VPN:" + vpn + " of Process " + processID);
TranslationEntry t = pageTable[vpn];
if (!t.valid) {
// System.out.println("Allocating VPN: " + t.vpn);
lock.acquire();
if (UserKernel.freePages.size() > 0) {
int ppn = ((Integer) UserKernel.freePages.removeFirst()).intValue();
t.valid = true;
if (!t.dirty) {
t.ppn = ppn;
IPT[ppn] = new IPTEntry();
IPT[ppn].process = this;
IPT[ppn].tE = t;
boolean isCoffSection = false;
for (int s = 0; s < coff.getNumSections(); s++) {
if (isCoffSection) {
break;
}
CoffSection section = coff.getSection(s);
if (section.getFirstVPN() > t.vpn) {
continue;
}
for (int i = 0; i < section.getLength(); i++) {
int svpn = section.getFirstVPN() + i;
if (svpn == t.vpn) {
section.loadPage(i, pinVirtualPage(t.vpn, false));
// System.out.println("VPN \"" + t.vpn + "\" is a COFF section");
// System.out.println("COFF section loaded into VPN \"" + t.vpn + "\" PPN \"" +
// t.ppn + "\"");
isCoffSection = true;
break;
}
}
}
if (!isCoffSection) {
// System.out.println("VPN \"" + t.vpn + "\" is NOT a COFF section");
// System.out.println("PPN \"" + t.ppn + "\" Zero'd Out");
byte[] data = new byte[Processor.pageSize];
// writeVirtualMemory(t.vpn, data, 0, Processor.pageSize);
byte[] memory = Machine.processor().getMemory();
System.arraycopy(data, 0, memory, t.ppn * Processor.pageSize, Processor.pageSize);
}
} else // Dirty
{
// System.out.println("VPN \"" + t.vpn + "\" has been swapped out, swaping into
// PPN \"" + ppn + "\"");
int spn = t.ppn;
byte[] data = new byte[pageSize];
byte[] memory = Machine.processor().getMemory();
OpenFile swap = ThreadedKernel.fileSystem.open(".Nachos.swp", false);
swap.read(spn * pageSize, memory, ppn * pageSize, pageSize);
swap.close();
t.ppn = ppn;
// System.out.println(spn);
freeSwapPages.set(spn, true);
IPT[ppn] = new IPTEntry();
IPT[ppn].process = this;
IPT[ppn].tE = t;
// System.out.println("SPN \"" + spn + "\" has been swapped in.");
}
} else {
syncTLB();
// Clock Algorithm
unpinnedPageLock.acquire();
int numPinnedPages = 0;
while (IPT[victim] == null || IPT[victim].tE.used || IPT[victim].pinCount) {
if (IPT[victim] != null) {
IPT[victim].tE.used = false;
// System.out.println("PPN " + victim + " is used.");
}
if (IPT[victim].pinCount) {
numPinnedPages++;
// System.out.println("PPN " + victim + " is pinned.");
}
if (numPinnedPages == IPT.length) unpinnedPage.sleep();
// System.out.println("This Process is " + this.processID + " and the IPT's
// process is " + IPT[victim].processID);
victim = (victim + 1) % Machine.processor().getNumPhysPages();
}
// System.out.println("PPN " + victim + " will be evicted.");
unpinnedPageLock.release();
int evict = IPT[victim].tE.vpn;
VMProcess evictedOwner = IPT[victim].process;
int evictedPPN = victim;
victim = (victim + 1) % Machine.processor().getNumPhysPages();
// System.out.println("Not enough pysical memory, evicting VPN \"" + evict + "\" of process
// " + evictedOwner.processID);
// Swap Files
if (evictedOwner.isDirty(evict)) {
// System.out.println("VPN \"" + evict + "\" is dirty, swapping out.");
OpenFile swap = ThreadedKernel.fileSystem.open(".Nachos.swp", false);
int spn = 0;
for (spn = 0; spn < freeSwapPages.size(); spn++) {
if (freeSwapPages.get(spn)) {
break;
}
}
if (spn == freeSwapPages.size()) {
freeSwapPages.add(false);
} else {
freeSwapPages.set(spn, false);
}
UserKernel.freePages.add(evictedPPN);
byte[] memory = Machine.processor().getMemory();
swap.write(spn * pageSize, memory, evictedPPN * pageSize, pageSize);
swap.close();
if (evictedOwner.processID != this.processID) {
evictedOwner.evict(evict, spn);
} else {
pageTable[evict].ppn = spn;
pageTable[evict].valid = false;
}
for (int i = 0; i < Machine.processor().getTLBSize(); i++) {
TranslationEntry tE = Machine.processor().readTLBEntry(i);
if (tE.vpn == evict && tE.ppn == evictedPPN) {
// System.out.println("TLBEntry " + i + " invalid");
tE.valid = false;
Machine.processor().writeTLBEntry(i, tE);
}
}
lock.release();
// System.out.println("VPN \"" + evict + "\" of Process " + this.processID + "
// swapped out to SPN \"" + spn + "\".");
// Machine.processor().readTLBEntry(evict).valid = false;
allocatePage(vpn);
return;
} else {
if (evictedOwner.processID != this.processID) {
// System.out.println("Evicted VPN " + evict + " of Process " + this.processID);
evictedOwner.evict(evict);
} else {
pageTable[evict].valid = false;
}
UserKernel.freePages.add(evictedPPN);
for (int i = 0; i < Machine.processor().getTLBSize(); i++) {
TranslationEntry tE = Machine.processor().readTLBEntry(i);
if (tE.vpn == evict && tE.ppn == evictedPPN) {
// System.out.println("TLBEntry " + i + " invalid");
tE.valid = false;
Machine.processor().writeTLBEntry(i, tE);
}
}
lock.release();
allocatePage(vpn);
return;
}
}
lock.release();
}
for (int i = 0; i < Machine.processor().getTLBSize(); i++) {
TranslationEntry tE = Machine.processor().readTLBEntry(i);
if (!tE.valid) {
// System.out.println("Evicted TLBEntry " + i);
Machine.processor().writeTLBEntry(i, t);
// System.out.println(t.valid);
return;
}
}
syncTLB();
int evictedEntry = (int) (Math.random() * Machine.processor().getTLBSize());
TranslationEntry tE = Machine.processor().readTLBEntry(evictedEntry);
pageTable[tE.vpn] = tE;
Machine.processor().writeTLBEntry(evictedEntry, t);
// System.out.println("Evicted TLBEntry " + evictedEntry + " randomly");
// System.out.println("TE entered is VPN \"" + t.vpn + "\" PPN \"" + t.ppn + "\"");
}
public void evict(int vpn, int spn) {
pageTable[vpn].ppn = spn;
pageTable[vpn].valid = false;
}
public void evict(int vpn) {
pageTable[vpn].valid = false;
}
public boolean isDirty(int vpn) {
return pageTable[vpn].dirty;
}
private static final int pageSize = Processor.pageSize;
private static final char dbgProcess = 'a';
private static final char dbgVM = 'v';
private static int victim = 0;
private static LinkedList<Boolean> freeSwapPages = new LinkedList<Boolean>();
private static IPTEntry[] IPT = new IPTEntry[Machine.processor().getNumPhysPages()];
private class IPTEntry {
public VMProcess process;
public TranslationEntry tE;
public boolean pinCount;
}
public static Lock unpinnedPageLock = new Lock();
public static Condition unpinnedPage = new Condition(unpinnedPageLock);
public static Lock lock = new Lock();
private int[] savedState = new int[Machine.processor().getTLBSize()];
}