Changed back to lottery scheduler, disabled debug
[tpg/acess2.git] / Kernel / threads.c
index 2670a1d..325fa74 100644 (file)
@@ -7,13 +7,22 @@
 #include <threads.h>
 #include <errno.h>
 
+// Configuration
 #define DEBUG_TRACE_TICKETS    0       // Trace ticket counts
 #define DEBUG_TRACE_STATE      0       // Trace state changes (sleep/wake)
 
+// --- Schedulers ---
+#define SCHED_UNDEF    0
+#define SCHED_LOTTERY  1       // Lottery scheduler
+#define SCHED_RR_SIM   2       // Single Queue Round Robin
+#define SCHED_RR_PRI   3       // Multi Queue Round Robin
+// Set scheduler type
+#define SCHEDULER_TYPE SCHED_LOTTERY
+
 // === CONSTANTS ===
 #define        DEFAULT_QUANTUM 10
-#define        DEFAULT_TICKETS 5
-#define MAX_TICKETS            10
+#define        DEFAULT_PRIORITY        5
+#define MIN_PRIORITY           10
 const enum eConfigTypes        cCONFIG_TYPES[] = {
        CFGT_HEAPSTR,   // e.g. CFG_VFS_CWD
        CFGT_INT,       // e.g. CFG_VFS_MAXFILES
@@ -36,14 +45,13 @@ tThread     *Threads_CloneTCB(Uint *Err, Uint Flags);
  int   Threads_WaitTID(int TID, int *status);
 tThread        *Threads_GetThread(Uint TID);
 void   Threads_AddToDelete(tThread *Thread);
-tThread        *Threads_int_GetPrev(tThread **List, tThread *Thread);
+tThread        *Threads_int_DelFromQueue(tThread **List, tThread *Thread);
 void   Threads_Exit(int TID, int Status);
 void   Threads_Kill(tThread *Thread, int Status);
 void   Threads_Yield(void);
 void   Threads_Sleep(void);
  int   Threads_Wake(tThread *Thread);
 void   Threads_AddActive(tThread *Thread);
-void   Threads_int_AddActive(tThread *Thread);
 tThread        *Threads_RemActive(void);
  int   Threads_GetPID(void);
  int   Threads_GetTID(void);
@@ -52,6 +60,7 @@ tUID  Threads_GetUID(void);
 tGID   Threads_GetGID(void);
  int   Threads_SetGID(Uint *Errno, tUID ID);
 void   Threads_Dump(void);
+void   Threads_DumpActive(void);
 void   Mutex_Acquire(tMutex *Mutex);
 void   Mutex_Release(tMutex *Mutex);
  int   Mutex_IsLocked(tMutex *Mutex);
@@ -64,21 +73,32 @@ tThread     gThreadZero = {
        ThreadName:     "ThreadZero",   // Name
        Quantum: DEFAULT_QUANTUM,       // Default Quantum
        Remaining:      DEFAULT_QUANTUM,        // Current Quantum
-       NumTickets:     DEFAULT_TICKETS // Number of tickets
+       Priority:       DEFAULT_PRIORITY        // Number of tickets
        };
 // -- Processes --
 // --- Locks ---
 tShortSpinlock glThreadListLock;       ///\note NEVER use a heap function while locked
 // --- Current State ---
 volatile int   giNumActiveThreads = 0; // Number of threads on the active queue
-volatile int   giFreeTickets = 0;      // Number of tickets held by non-scheduled threads
 volatile Uint  giNextTID = 1;  // Next TID to allocate
 // --- Thread Lists ---
 tThread        *gAllThreads = NULL;            // All allocated threads
-tThread        *gActiveThreads = NULL;         // Currently Running Threads
 tThread        *gSleepingThreads = NULL;       // Sleeping Threads
 tThread        *gDeleteThreads = NULL;         // Threads to delete
  int   giNumCPUs = 1;  // Number of CPUs
+BOOL     gaThreads_NoTaskSwitch[MAX_CPUS];     // Disables task switches for each core (Pseudo-IF)
+// --- Scheduler Types ---
+#if SCHEDULER_TYPE == SCHED_LOTTERY
+const int      caiTICKET_COUNTS[MIN_PRIORITY+1] = {100,81,64,49,36,25,16,9,4,1,0};
+volatile int   giFreeTickets = 0;      // Number of tickets held by non-scheduled threads
+tThread        *gActiveThreads = NULL;         // Currently Running Threads
+#elif SCHEDULER_TYPE == SCHED_RR_SIM
+tThread        *gActiveThreads = NULL;         // Currently Running Threads
+#elif SCHEDULER_TYPE == SCHED_RR_PRI
+tThread        *gaActiveThreads[MIN_PRIORITY+1];       // Active threads for each priority level
+#else
+# error "Unkown scheduler type"
+#endif
 
 // === CODE ===
 /**
@@ -90,9 +110,13 @@ void Threads_Init(void)
        ArchThreads_Init();
        
        // Create Initial Task
+       #if SCHEDULER_TYPE == SCHED_RR_PRI
+       gaActiveThreads[gThreadZero.Priority] = &gThreadZero;
+       #else
        gActiveThreads = &gThreadZero;
+       #endif
+       
        gAllThreads = &gThreadZero;
-       //giFreeTickets = gThreadZero.NumTickets;       // Not needed, as ThreadZero is scheduled
        giNumActiveThreads = 1;
                
        Proc_Start();
@@ -136,31 +160,50 @@ char *Threads_GetName(tTID ID)
 }
 
 /**
- * \fn void Threads_SetTickets(tThread *Thread, int Num)
- * \brief Sets the 'priority' of a task
+ * \fn void Threads_SetPriority(tThread *Thread, int Pri)
+ * \brief Sets the priority of a task
  * \param Thread       Thread to update ticket count (NULL means current thread)
- * \param Num  New ticket count (must be >= 0, clipped to \a MAX_TICKETS)
+ * \param Pri  New priority
  */
-void Threads_SetTickets(tThread *Thread, int Num)
+void Threads_SetPriority(tThread *Thread, int Pri)
 {
        // Get current thread
        if(Thread == NULL)      Thread = Proc_GetCurThread();
        // Bounds checking
-       if(Num < 0)     return;
-       if(Num > MAX_TICKETS)   Num = MAX_TICKETS;
+       // - If < 0, set to lowest priority
+       if(Pri < 0)     Pri = MIN_PRIORITY;
+       if(Pri > MIN_PRIORITY)  Pri = MIN_PRIORITY;
        
+       // Do we actually have to do anything?
+       if( Pri == Thread->Priority )   return;
+       
+       #if SCHEDULER_TYPE == SCHED_RR_PRI
+       SHORTLOCK( &glThreadListLock );
+       // Remove from old priority
+       Threads_int_DelFromQueue( &gaActiveThreads[Thread->Priority], Thread );
+       // And add to new
+       Thread->Next = gaActiveThreads[Pri];
+       gaActiveThreads[Pri] = Thread;
+       Thread->Priority = Pri;
+       SHORTREL( &glThreadListLock );
+       #else
        // If this isn't the current thread, we need to lock
-       if( Thread != Proc_GetCurThread() ) {
+       if( Thread != Proc_GetCurThread() )
+       {
                SHORTLOCK( &glThreadListLock );
-               giFreeTickets -= Thread->NumTickets - Num;
-               Thread->NumTickets = Num;
-               #if DEBUG_TRACE_TICKETS
+               
+               #if SCHEDULER_TYPE == SCHED_LOTTERY
+               giFreeTickets -= caiTICKET_COUNTS[Thread->Priority] - caiTICKET_COUNTS[Pri];
+               # if DEBUG_TRACE_TICKETS
                Log("Threads_SetTickets: new giFreeTickets = %i", giFreeTickets);
+               # endif
                #endif
+               Thread->Priority = Pri;
                SHORTREL( &glThreadListLock );
        }
        else
-               Thread->NumTickets = Num;
+               Thread->Priority = Pri;
+       #endif
 }
 
 /**
@@ -208,7 +251,7 @@ tThread *Threads_CloneTCB(Uint *Err, Uint Flags)
        
        // Set State
        new->Remaining = new->Quantum = cur->Quantum;
-       new->NumTickets = cur->NumTickets;
+       new->Priority = cur->Priority;
        
        // Set Signal Handlers
        new->CurFaultNum = 0;
@@ -362,33 +405,36 @@ void Threads_AddToDelete(tThread *Thread)
 }
 
 /**
- * \brief Gets the previous entry in a thead linked list
+ * \brief Deletes an entry from a list
  * \param List Pointer to the list head
  * \param Thread       Thread to find
- * \return Thread before \a Thread on \a List
- * \note This uses a massive hack of assuming that the first field in the
- *       structure is the .Next pointer. By doing this, we can return \a List
- *       as a (tThread*) and simplify other code.
+ * \return \a Thread
  */
-tThread *Threads_int_GetPrev(tThread **List, tThread *Thread)
+tThread *Threads_int_DelFromQueue(tThread **List, tThread *Thread)
 {
-       tThread *ret;
-       // First Entry
-       if(*List == Thread) {
-               return (tThread*)List;
+       tThread *ret, *prev = NULL;
+       
+       for(ret = *List;
+               ret && ret != Thread;
+               prev = ret, ret = ret->Next
+               );
+       
+       // Is the thread on the list
+       if(!ret) {
+               //LogF("%p(%s) is not on list %p\n", Thread, Thread->ThreadName, List);
+               return NULL;
+       }
+       
+       if( !prev ) {
+               *List = Thread->Next;
+               //LogF("%p(%s) removed from head of %p\n", Thread, Thread->ThreadName, List);
        }
-       // Or not
        else {
-               for(ret = *List;
-                       ret->Next && ret->Next != Thread;
-                       ret = ret->Next
-                       );
-               // Error if the thread is not on the list
-               if(!ret->Next || ret->Next != Thread) {
-                       return NULL;
-               }
+               prev->Next = Thread->Next;
+               //LogF("%p(%s) removed from %p (prev=%p)\n", Thread, Thread->ThreadName, List, prev);
        }
-       return ret;
+       
+       return Thread;
 }
 
 /**
@@ -415,7 +461,6 @@ void Threads_Exit(int TID, int Status)
  */
 void Threads_Kill(tThread *Thread, int Status)
 {
-       tThread *prev;
        tMsg    *msg;
        
        // TODO: Kill all children
@@ -438,35 +483,40 @@ void Threads_Kill(tThread *Thread, int Status)
        // Lock thread (stop us recieving messages)
        SHORTLOCK( &Thread->IsLocked );
        
+       // Clear Message Queue
+       while( Thread->Messages )
+       {
+               msg = Thread->Messages->Next;
+               free( Thread->Messages );
+               Thread->Messages = msg;
+       }
+       
        // Lock thread list
        SHORTLOCK( &glThreadListLock );
        
-       // Get previous thread on list
-       prev = Threads_int_GetPrev( &gActiveThreads, Thread );
-       if(!prev) {
+       // Delete from active list
+       #if SCHEDULER_TYPE == SCHED_RR_PRI
+       if( !Threads_int_DelFromQueue( &gaActiveThreads[Thread->Priority], Thread ) )
+       #else
+       if( !Threads_int_DelFromQueue( &gActiveThreads, Thread ) )
+       #endif
+       {
                Warning("Proc_Exit - Current thread is not on the active queue");
                SHORTREL( &glThreadListLock );
                SHORTREL( &Thread->IsLocked );
                return;
        }
        
-       // Clear Message Queue
-       while( Thread->Messages )
-       {
-               msg = Thread->Messages->Next;
-               free( Thread->Messages );       // BIG NO-NO
-               Thread->Messages = msg;
-       }
-       
        // Ensure that we are not rescheduled
        Thread->Remaining = 0;  // Clear Remaining Quantum
        Thread->Quantum = 0;    // Clear Quantum to indicate dead thread
-       prev->Next = Thread->Next;      // Remove from active
        
        // Update bookkeeping
        giNumActiveThreads --;
+       #if SCHEDULER_TYPE == SCHED_LOTTERY
        if( Thread != Proc_GetCurThread() )
-               giFreeTickets -= Thread->NumTickets;
+               giFreeTickets -= caiTICKET_COUNTS[ Thread->Priority ];
+       #endif
        
        // Save exit status
        Thread->RetStatus = Status;
@@ -553,8 +603,6 @@ void Threads_Sleep(void)
  */
 int Threads_Wake(tThread *Thread)
 {
-       tThread *prev;
-       
        if(!Thread)
                return -EINVAL;
        
@@ -565,15 +613,16 @@ int Threads_Wake(tThread *Thread)
                return -EALREADY;
        
        case THREAD_STAT_SLEEPING:
+               SHORTLOCK( &glThreadListLock );
                // Remove from sleeping queue
-               prev = Threads_int_GetPrev(&gSleepingThreads, Thread);
-               prev->Next = Thread->Next;
+               Threads_int_DelFromQueue(&gSleepingThreads, Thread);
                
-               Threads_int_AddActive( Thread );
+               Threads_AddActive( Thread );
                
                #if DEBUG_TRACE_STATE
                Log("Threads_Sleep: %p (%i %s) woken", Thread, Thread->TID, Thread->ThreadName);
                #endif
+               SHORTREL( &glThreadListLock );
                return -EOK;
        
        case THREAD_STAT_WAITING:
@@ -601,9 +650,7 @@ int Threads_WakeTID(tTID TID)
         int    ret;
        if(!thread)
                return -ENOENT;
-       SHORTLOCK( &glThreadListLock );
        ret = Threads_Wake( thread );
-       SHORTREL( &glThreadListLock );
        //Log_Debug("Threads", "TID %i woke %i (%p)", Threads_GetTID(), TID, thread);
        return ret;
 }
@@ -614,30 +661,31 @@ int Threads_WakeTID(tTID TID)
 void Threads_AddActive(tThread *Thread)
 {
        SHORTLOCK( &glThreadListLock );
-       Threads_int_AddActive(Thread);
-       SHORTREL( &glThreadListLock );
-}
-
-/**
- * \brief Adds a thread to the active queue
- * \note This version MUST have the thread list lock held
- */
-void Threads_int_AddActive(tThread *Thread)
-{
-       // Add to active list
-       Thread->Next = gActiveThreads;
-       gActiveThreads = Thread;
+       
        // Set state
        Thread->Status = THREAD_STAT_ACTIVE;
        Thread->CurCPU = -1;
+       // Add to active list
+       #if SCHEDULER_TYPE == SCHED_RR_PRI
+       Thread->Next = gaActiveThreads[Thread->Priority];
+       gaActiveThreads[Thread->Priority] = Thread;
+       #else
+       Thread->Next = gActiveThreads;
+       gActiveThreads = Thread;
+       #endif
        
        // Update bookkeeping
        giNumActiveThreads ++;
-       giFreeTickets += Thread->NumTickets;
        
-       #if DEBUG_TRACE_TICKETS
-       Log("Threads_int_AddActive: new giFreeTickets = %i", giFreeTickets);
+       #if SCHEDULER_TYPE == SCHED_LOTTERY
+       giFreeTickets += caiTICKET_COUNTS[ Thread->Priority ];
+       # if DEBUG_TRACE_TICKETS
+       Log("Threads_AddActive: %p %i (%s) added, new giFreeTickets = %i",
+               Thread, Thread->TID, Thread->ThreadName, giFreeTickets);
+       # endif
        #endif
+       
+       SHORTREL( &glThreadListLock );
 }
 
 /**
@@ -648,12 +696,33 @@ void Threads_int_AddActive(tThread *Thread)
 tThread *Threads_RemActive(void)
 {
        tThread *ret = Proc_GetCurThread();
-       tThread *prev = Threads_int_GetPrev(&gActiveThreads, ret);
-       if(!prev)       return NULL;
+       
+       SHORTLOCK( &glThreadListLock );
+       
+       // Delete from active queue
+       #if SCHEDULER_TYPE == SCHED_RR_PRI
+       if( !Threads_int_DelFromQueue(&gaActiveThreads[ret->Priority], ret) )
+       #else
+       if( !Threads_int_DelFromQueue(&gActiveThreads, ret) )
+       #endif
+       {
+               SHORTREL( &glThreadListLock );
+               return NULL;
+       }
+       
        ret->Remaining = 0;
        ret->CurCPU = -1;
-       prev->Next = ret->Next;
+       
        giNumActiveThreads --;
+       // no need to decrement tickets, scheduler did it for us
+       
+       #if SCHEDULER_TYPE == SCHED_LOTTERY && DEBUG_TRACE_TICKETS
+       Log("Threads_RemActive: %p %i (%s) removed, giFreeTickets = %i",
+               ret, ret->TID, ret->ThreadName, giFreeTickets);
+       #endif
+       
+       SHORTREL( &glThreadListLock );
+       
        return ret;
 }
 
@@ -748,22 +817,47 @@ int Threads_SetGID(Uint *Errno, tGID ID)
 
 /**
  * \fn void Threads_Dump(void)
- * \brief Dums a list of currently running threads
  */
-void Threads_Dump(void)
+void Threads_DumpActive(void)
 {
        tThread *thread;
+       #if SCHEDULER_TYPE == SCHED_RR_PRI
+        int    i;
+       #endif
+       
+       Log("Active Threads: (%i reported)", giNumActiveThreads);
        
-       Log("Active Threads:");
-       for(thread=gActiveThreads;thread;thread=thread->Next)
+       #if SCHEDULER_TYPE == SCHED_RR_PRI
+       for( i = 0; i < MIN_PRIORITY+1; i++ )
        {
-               Log(" %i (%i) - %s (CPU %i)",
-                       thread->TID, thread->TGID, thread->ThreadName, thread->CurCPU);
-               if(thread->Status != THREAD_STAT_ACTIVE)
-                       Log("  ERROR State (%i) != THREAD_STAT_ACTIVE (%i)", thread->Status, THREAD_STAT_ACTIVE);
-               Log("  %i Tickets, Quantum %i", thread->NumTickets, thread->Quantum);
-               Log("  KStack 0x%x", thread->KernelStack);
+               for(thread=gaActiveThreads[i];thread;thread=thread->Next)
+       #else
+               for(thread=gActiveThreads;thread;thread=thread->Next)
+       #endif
+               {
+                       Log(" %i (%i) - %s (CPU %i)",
+                               thread->TID, thread->TGID, thread->ThreadName, thread->CurCPU);
+                       if(thread->Status != THREAD_STAT_ACTIVE)
+                               Log("  ERROR State (%i) != THREAD_STAT_ACTIVE (%i)", thread->Status, THREAD_STAT_ACTIVE);
+                       Log("  Priority %i, Quantum %i", thread->Priority, thread->Quantum);
+                       Log("  KStack 0x%x", thread->KernelStack);
+               }
+       
+       #if SCHEDULER_TYPE == SCHED_RR_PRI
        }
+       #endif
+}
+
+/**
+ * \fn void Threads_Dump(void)
+ * \brief Dumps a list of currently running threads
+ */
+void Threads_Dump(void)
+{
+       tThread *thread;
+       
+       Log("--- Thread Dump ---");
+       Threads_DumpActive();
        
        Log("All Threads:");
        for(thread=gAllThreads;thread;thread=thread->GlobalNext)
@@ -771,7 +865,7 @@ void Threads_Dump(void)
                Log(" %i (%i) - %s (CPU %i)",
                        thread->TID, thread->TGID, thread->ThreadName, thread->CurCPU);
                Log("  State %i", thread->Status);
-               Log("  %i Tickets, Quantum %i", thread->NumTickets, thread->Quantum);
+               Log("  Priority %i, Quantum %i", thread->Priority, thread->Quantum);
                Log("  KStack 0x%x", thread->KernelStack);
        }
 }
@@ -784,9 +878,16 @@ void Threads_Dump(void)
 tThread *Threads_GetNextToRun(int CPU, tThread *Last)
 {
        tThread *thread;
-        int    ticket;
-        int    number; 
        
+       // If this CPU has the lock, we must let it complete
+       if( CPU_HAS_LOCK( &glThreadListLock ) )
+               return Last;
+       
+       // Don't change threads if the current CPU has switches disabled
+       if( gaThreads_NoTaskSwitch[CPU] )
+               return Last;
+
+
        // Lock thread list
        SHORTLOCK( &glThreadListLock );
        
@@ -820,85 +921,166 @@ tThread *Threads_GetNextToRun(int CPU, tThread *Last)
                return NULL;
        }
        
+       #if SCHEDULER_TYPE != SCHED_RR_PRI
        // Special case: 1 thread
        if(giNumActiveThreads == 1) {
                if( gActiveThreads->CurCPU == -1 )
                        gActiveThreads->CurCPU = CPU;
+               
                SHORTREL( &glThreadListLock );
+               
                if( gActiveThreads->CurCPU == CPU )
                        return gActiveThreads;
+               
                return NULL;    // CPU has nothing to do
        }
+       #endif
        
        // Allow the old thread to be scheduled again
        if( Last ) {
                if( Last->Status == THREAD_STAT_ACTIVE ) {
-                       giFreeTickets += Last->NumTickets;
-                       #if DEBUG_TRACE_TICKETS
+                       #if SCHEDULER_TYPE == SCHED_LOTTERY
+                       giFreeTickets += caiTICKET_COUNTS[ Last->Priority ];
+                       # if DEBUG_TRACE_TICKETS
                        LogF(" CPU %i released %p (%i %s) into the pool (%i tickets in pool)\n",
                                CPU, Last, Last->TID, Last->ThreadName, giFreeTickets);
+                       # endif
                        #endif
                }
-               #if DEBUG_TRACE_TICKETS
+               #if SCHEDULER_TYPE == SCHED_LOTTERY && DEBUG_TRACE_TICKETS
                else
-                       LogF(" %p (%s)->Status = %i (Released)\n", Last, Last->ThreadName, Last->Status);
+                       LogF(" CPU %i released %p (%i %s)->Status = %i (Released)\n",
+                               CPU, Last, Last->TID, Last->ThreadName, Last->Status);
                #endif
                Last->CurCPU = -1;
        }
        
-       #if 1
-       number = 0;
-       for(thread = gActiveThreads; thread; thread = thread->Next) {
-               if(thread->CurCPU >= 0) continue;
-               number += thread->NumTickets;
-       }
-       if(number != giFreeTickets) {
-               Panic("Bookkeeping fail (giFreeTickets(%i) != number(%i)) - CPU%i",
-                       giFreeTickets, number, CPU);
-       }
-       #endif
-       
-       // No free tickets (all tasks delegated to cores)
-       if( giFreeTickets == 0 ) {
-               SHORTREL(&glThreadListLock);
-               return NULL;
+       // ---
+       // Lottery Scheduler
+       // ---
+       #if SCHEDULER_TYPE == SCHED_LOTTERY
+       {
+                int    ticket, number;
+               # if 1
+               number = 0;
+               for(thread = gActiveThreads; thread; thread = thread->Next) {
+                       if(thread->CurCPU >= 0) continue;
+                       if(thread->Status != THREAD_STAT_ACTIVE)
+                               Panic("Bookkeeping fail - %p %i(%s) is on the active queue with a status of %i",
+                                       thread, thread->TID, thread->ThreadName, thread->Status);
+                       if(thread->Next == thread) {
+                               Panic("Bookkeeping fail - %p %i(%s) loops back on itself",
+                                       thread, thread->TID, thread->ThreadName, thread->Status);
+                       }
+                       number += caiTICKET_COUNTS[ thread->Priority ];
+               }
+               if(number != giFreeTickets) {
+                       Panic("Bookkeeping fail (giFreeTickets(%i) != number(%i)) - CPU%i",
+                               giFreeTickets, number, CPU);
+               }
+               # endif
+               
+               // No free tickets (all tasks delegated to cores)
+               if( giFreeTickets == 0 ) {
+                       SHORTREL(&glThreadListLock);
+                       return NULL;
+               }
+               
+               // Get the ticket number
+               ticket = number = rand() % giFreeTickets;
+               
+               // Find the next thread
+               for(thread=gActiveThreads;thread;thread=thread->Next)
+               {
+                       if(thread->CurCPU >= 0) continue;
+                       if( caiTICKET_COUNTS[ thread->Priority ] > number)      break;
+                       number -= caiTICKET_COUNTS[ thread->Priority ];
+               }
+               
+               // If we didn't find a thread, something went wrong
+               if(thread == NULL)
+               {
+                       number = 0;
+                       for(thread=gActiveThreads;thread;thread=thread->Next) {
+                               if(thread->CurCPU >= 0) continue;
+                               number += caiTICKET_COUNTS[ thread->Priority ];
+                       }
+                       Panic("Bookeeping Failed - giFreeTickets(%i) > true count (%i)",
+                               giFreeTickets, number);
+               }
+               # if DEBUG_TRACE_TICKETS
+               LogF(" CPU%i giFreeTickets = %i, running %p (%i %s CPU=%i)\n",
+                       CPU, giFreeTickets, thread, thread->TID, thread->ThreadName, thread->CurCPU);
+               # endif
+               
+               giFreeTickets -= caiTICKET_COUNTS[ thread->Priority ];
        }
        
-       // Get the ticket number
-       ticket = number = rand() % giFreeTickets;
-       
-       // Find the next thread
-       for(thread=gActiveThreads;thread;thread=thread->Next)
+       // ---
+       // Priority based round robin scheduler
+       // ---
+       #elif SCHEDULER_TYPE == SCHED_RR_PRI
        {
-               if(thread->CurCPU >= 0) continue;
-               if(thread->NumTickets > number) break;
-               number -= thread->NumTickets;
+                int    i;
+               for( i = 0; i < MIN_PRIORITY + 1; i ++ )
+               {
+                       for(thread = gaActiveThreads[i]; thread; thread = thread->Next)
+                       {
+                               if( thread->CurCPU == -1 )      break;
+                       }
+                       // If we fall onto the same queue again, special handling is
+                       // needed
+                       if( i == Last->Priority ) {
+                               tThread *savedThread = thread;
+                               
+                               // Find the next unscheduled thread in the list
+                               for( thread = Last->Next; thread; thread = thread->Next )
+                               {
+                                       if( thread->CurCPU == -1 )      break;
+                               }
+                               // If we don't find anything after, just use the one 
+                               // found above.
+                               if( !thread )   thread = savedThread;
+                       }
+                       // Found a thread? Schedule it!
+                       if( thread )    break;
+               }
+               
+               // Anything to do?
+               if( !thread ) {
+                       SHORTREL(&glThreadListLock);
+                       return NULL;
+               }
        }
-       // Error Check
-       if(thread == NULL)
-       {
-               number = 0;
-               for(thread=gActiveThreads;thread;thread=thread->Next) {
-                       if(thread->CurCPU >= 0) continue;
-                       number += thread->NumTickets;
+       #elif SCHEDULER_TYPE == SCHED_RR_SIM
+       {               
+               // Find the next unscheduled thread in the list
+               for( thread = Last->Next; thread; thread = thread->Next )
+               {
+                       if( thread->CurCPU == -1 )      break;
+               }
+               // If we don't find anything after, search from the beginning
+               if( !thread )
+               {
+                       for(thread = gActiveThreads; thread; thread = thread->Next)
+                       {
+                               if( thread->CurCPU == -1 )      break;
+                       }       
+               }
+               
+               // Anything to do?
+               if( !thread ) {
+                       SHORTREL(&glThreadListLock);
+                       return NULL;
                }
-               Panic("Bookeeping Failed - giFreeTickets(%i) > true count (%i)",
-                       giFreeTickets, number);
        }
-       #if DEBUG_TRACE_TICKETS
-       LogF(" CPU%i giFreeTickets = %i\n", CPU, giFreeTickets);
+       #else
+       # error "Unimplemented scheduling algorithm"
        #endif
        
        // Make the new thread non-schedulable
-       giFreeTickets -= thread->NumTickets;    
        thread->CurCPU = CPU;
        
-       //Threads_Dump();
-       #if DEBUG_TRACE_TICKETS
-       LogF(" CPU%i giFreeTickets = %i, giving %p (%i %s CPU=%i)\n",
-               CPU, giFreeTickets, thread, thread->TID, thread->ThreadName, thread->CurCPU);
-       #endif
-       
        SHORTREL( &glThreadListLock );
        
        return thread;
@@ -938,7 +1120,7 @@ void Mutex_Acquire(tMutex *Mutex)
        if( Mutex->Owner ) {
                SHORTLOCK( &glThreadListLock );
                // - Remove from active list
-               Threads_RemActive();
+               us = Threads_RemActive();
                // - Mark as sleeping
                us->Status = THREAD_STAT_OFFSLEEP;
                
@@ -974,9 +1156,18 @@ void Mutex_Release(tMutex *Mutex)
        if( Mutex->Waiting ) {
                Mutex->Owner = Mutex->Waiting;  // Set owner
                Mutex->Waiting = Mutex->Waiting->Next;  // Next!
+               // Reset ->LastWaiting to NULL if we have just removed the last waiting thread
+               // 2010-10-02 21:50 - Comemerating the death of the longest single
+               //                    blocker in the Acess2 history. REMEMBER TO
+               //                    FUCKING MAINTAIN YOUR FUCKING LISTS DIPWIT
+               if( Mutex->LastWaiting == Mutex->Owner )
+                       Mutex->LastWaiting = NULL;
+               
                // Wake new owner
-               Threads_AddActive(Mutex->Owner);
-               //Log("Mutex %p Woke %p", Mutex, Mutex->Owner);
+               SHORTLOCK( &glThreadListLock );
+               if( Mutex->Owner->Status != THREAD_STAT_ACTIVE )
+                       Threads_AddActive(Mutex->Owner);
+               SHORTREL( &glThreadListLock );
        }
        else {
                Mutex->Owner = NULL;
@@ -995,6 +1186,7 @@ int Mutex_IsLocked(tMutex *Mutex)
 
 // === EXPORTS ===
 EXPORT(Threads_GetUID);
+EXPORT(Threads_GetGID);
 EXPORT(Mutex_Acquire);
 EXPORT(Mutex_Release);
 EXPORT(Mutex_IsLocked);

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