TD2 II.3-4 Manage UserStack with Bitmap
Add a Semaphore to manage threads waiting list
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4 changed files with 67 additions and 11 deletions
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@ -6,15 +6,15 @@ void f(int c) {
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* a problem here, when executing a thread there is not 8 iterations.
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* This is like synchronisation */
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volatile int i;
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for (i=0;i<8;i++){
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for (i=0;i<16;i++){
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PutChar((char)c);
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}
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ThreadExit();
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}
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int main(){
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int i = 64;
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for (i=64; i < 68; i++){
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int i;
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for (i=65; i < 91; i++){
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ThreadCreate(f, i);
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}
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// PutString("end of main()\n");
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@ -21,7 +21,10 @@
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#include "noff.h"
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#include "syscall.h"
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#include "new"
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#ifdef CHANGED
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#include "synch.h"
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#include "bitmap.h"
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#endif //CHANGED
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//----------------------------------------------------------------------
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// SwapHeader
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// Do little endian to big endian conversion on the bytes in the
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@ -129,8 +132,17 @@ AddrSpace::AddrSpace (OpenFile * executable)
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pageTable[0].valid = FALSE; // Catch NULL dereference
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#ifdef CHANGED
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int bitmapSize = UserStacksAreaSize / UserStackSize;
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DEBUG('x', "Initialise thread counter\n");
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Threads = 1;
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threads = 1;
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DEBUG('x', "Initialise semaphores\n");
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semThreadsCounter = new Semaphore("AddrSpace_thread_counter", 1);
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semAllocateUserStack = new Semaphore("Stack Avaiable", 1);
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DEBUG('x', "Initialize memory map size:%d", bitmapSize);
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memoryMap = new BitMap(bitmapSize);
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memoryMap->Mark(0);
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#endif //CHANGED
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AddrSpaceList.Append(this);
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@ -147,6 +159,11 @@ AddrSpace::~AddrSpace ()
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pageTable = NULL;
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AddrSpaceList.Remove(this);
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#ifdef CHANGED
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delete semThreadsCounter;
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delete semAllocateUserStack;
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delete memoryMap;
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#endif
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}
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//----------------------------------------------------------------------
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@ -303,6 +320,25 @@ int
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AddrSpace::AllocateUserStack()
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{
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int memory = numPages * PageSize;
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return memory - 256;
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int bit;
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/* If we don't have any free slot, we can wait for one to be
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* freed by DeAllocateUserstack
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*/
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while ((bit = memoryMap->Find()) == - 1){
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DEBUG('x', "Can't allocate User Stack Wainting...\n");
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semAllocateUserStack->P();
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}
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int addr = memory - UserStackSize * bit;
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DEBUG('x', "Allocate User Stack bit %d, addr:%x\n", bit, addr);
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return addr;
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}
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void
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AddrSpace::DeAllocateUserStack(int addr){
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int memory = numPages * PageSize;
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int bit = (memory - addr) / UserStackSize;
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DEBUG('x', "Deallocate User Stack bit %d, addr:%x\n", bit, addr);
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memoryMap->Clear(bit);
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semAllocateUserStack->V();
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}
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#endif
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@ -19,6 +19,13 @@
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#include "noff.h"
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#include "list.h"
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#ifdef CHANGED
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#include "bitmap.h"
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class Semaphore;
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#define UserStackSize 256
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#endif //CHANGED
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#define UserStacksAreaSize 1024 // increase this as necessary!
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class AddrSpace:public dontcopythis
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@ -41,8 +48,12 @@ class AddrSpace:public dontcopythis
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// Dump program layout as SVG
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unsigned NumPages() { return numPages; }
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#ifdef CHANGED
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int Threads; // count number of threads into address space
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int threads; // count number of threads into address space
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Semaphore * semThreadsCounter;
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Semaphore * semAllocateUserStack;
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BitMap * memoryMap;
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int AllocateUserStack();
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void DeAllocateUserStack(int addr);
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#endif
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private:
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NoffHeader noffH; // Program layout
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@ -4,6 +4,7 @@
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#include "userthread.h"
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#include "syscall.h"
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#include "addrspace.h"
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#include "synch.h"
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static void StartUserThread( void * args ){
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@ -55,8 +56,10 @@ int do_ThreadCreate(int f, int arg){
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Thread * newThread = new Thread("new thread");
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// increment number of threads
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currentThread->space->Threads++;
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DEBUG('x', "Increase numbers of Threads:%d\n",currentThread->space->Threads);
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currentThread->space->semThreadsCounter->P();
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currentThread->space->threads++;
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currentThread->space->semThreadsCounter->V();
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DEBUG('x', "Increase numbers of Threads:%d\n",currentThread->space->threads);
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newThread->space = currentThread->space;
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newThread->Start(StartUserThread, args);
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@ -69,8 +72,14 @@ void do_ThreadExit(){
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// TODO: what should we do with thread space?
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// Probalely desallocate it... if no threads remain
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// currentThread->space->Threads--;
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DEBUG('x', "Decrease numbers of Threads:%d\n",currentThread->space->Threads);
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if ( --currentThread->space->Threads == 0){
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currentThread->space->semThreadsCounter->P();
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currentThread->space->threads--;
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currentThread->space->semThreadsCounter->V();
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int addr = machine->ReadRegister(StackReg);
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currentThread->space->DeAllocateUserStack(addr);
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DEBUG('x', "Decrease numbers of Threads:%d\n",currentThread->space->threads);
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if ( currentThread->space->threads == 0 ){
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// No threads remains, desallocate addrspace
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delete currentThread->space;
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interrupt->Powerdown();
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