/**
* 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;
}
}
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 + "\"");
}