Changeset 294 for soft/giet_vm/giet_kernel/ctx_handler.c

Timestamp:

Mar 26, 2014, 6:10:01 PM (11 years ago)

Author:

alain

Message:

Introducing support for IOPIC component.

File:

• soft/giet_vm/giet_kernel/ctx_handler.c (modified) (8 diffs)

soft/giet_vm/giet_kernel/ctx_handler.c

@@ -1 @@
-/////////////////////////////////////////////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////////////
 // File     : ctx_handler.c
 // Date     : 01/04/2012
 // Authors  : alain greiner & joel porquet
 // Copyright (c) UPMC-LIP6
-/////////////////////////////////////////////////////////////////////////////////////////
-// The ctx_handler.h and ctx_handler.c files are part of the GIET-VM nano-kernel.
-// This code is used to support context switch when several tasks are executing
-// in time multiplexing on a single processor.
-// The tasks are statically allocated to a processor in the boot phase, and
-// there is one private scheduler per processor. Each sheduler occupies 4K bytes, 
-// and contains up to 14 task contexts (task_id is from 0 to 13).
-// The task context [14] is reserved for the "idle" task that does nothing, and
-// is launched by the scheduler when there is no other runable task.
-/////////////////////////////////////////////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////////////
 
 #include <giet_config.h>
@@ -24 +15 @@
 #include <sys_handler.h>
 
-/////////////////////////////////////////////////////////////////////////////////////////
-// A task context is an array of 64 words = 256 bytes. 
-// It contains copies of processor registers (when the task is preempted):
-// - GPR[i], generally stored in slot (i). $0, $26 & $27 are not saved.
-// - HI & LO registers
-// - CP0 registers: EPC, SR, CR, BVAR 
-// - CP2 registers : PTPR 
-// It contains some general informations associated to the task:
-// - TTY    : TTY channel global index
-// - NIC    : NIC channel global index
-// - CMA    : CMA channel global index
-// - HBA    : HBA channel global index
-// - DMA    : DMA channel local index
-// - TIM    : TIM channel local index
-// - PTAB   : page table virtual base address 
-// - LTID   : Task local index (in scheduler)
-// - VSID   : Virtual space index
-// - RUN    : Task state (0 => sleeping / 1 => runnable ) 
-// - TRDID  : Thread ID index (in vspace)
-//
-// ctx[0]<- ***|ctx[8] <- $8 |ctx[16]<- $16|ctx[24]<- $24|ctx[32]<- EPC  |ctx[40]<- TTY
-// ctx[1]<- $1 |ctx[9] <- $9 |ctx[17]<- $17|ctx[25]<- $25|ctx[33]<- CR   |ctx[41]<- DMA
-// ctx[2]<- $2 |ctx[10]<- $10|ctx[18]<- $18|ctx[26]<- LO |ctx[34]<- SR   |ctx[42]<- NIC
-// ctx[3]<- $3 |ctx[11]<- $11|ctx[19]<- $19|ctx[27]<- HI |ctx[35]<- BVAR |ctx[43]<- TIM
-// ctx[4]<- $4 |ctx[12]<- $12|ctx[20]<- $20|ctx[28]<- $28|ctx[36]<- PTAB |ctx[44]<- HBA
-// ctx[5]<- $5 |ctx[13]<- $13|ctx[21]<- $21|ctx[29]<- SP |ctx[37]<- LTID |ctx[45]<- CMA 
-// ctx[6]<- $6 |ctx[14]<- $14|ctx[22]<- $22|ctx[30]<- $30|ctx[38]<- VSID |ctx[46]<- GTID
-// ctx[7]<- $7 |ctx[15]<- $15|ctx[23]<- $23|ctx[31]<- RA |ctx[39]<- PTPR |ctx[47]<- RUN
-//
-// ctx[48]<- TRDID
-//////////////////////////////////////////////////////////////////////////////////////////
-
 extern void _task_switch(unsigned int *, unsigned int *);
 
 /////////////////////////////////////////////////////////////////////////////////
-//    _ctx_switch()
 // This function performs a context switch between the running task
 // and  another task, using a round-robin sheduling policy between all
@@ -66 +24 @@
 // If the only runable task is the current task, return without context switch.
 // If there is no runable task, the scheduler switch to the default "idle" task.
-//
+/////////////////////////////////////////////////////////////////////////////////
 // Implementation note
 // The return address contained in $31 is saved in the current task context
@@ -74 +32 @@
 void _ctx_switch() 
 {
+    unsigned int gpid       = _get_procid();
+    unsigned int cluster_xy = gpid / NB_PROCS_MAX;
+    unsigned int lpid       = gpid % NB_PROCS_MAX;
+
     // get scheduler address
     static_scheduler_t* psched = (static_scheduler_t*)_get_sched();
@@ -105 +67 @@
     }
 
-    // no switch if no change
-    if (curr_task_id != next_task_id) 
-    {
 #if GIET_DEBUG_SWITCH
-_tty_get_lock( 0 );
-_puts("\n[GIET DEBUG] Context switch for processor ");
-_putd(_get_procid());
-_puts(" at cycle ");
-_putd(_get_proctime());
-_puts("\n");
-_puts(" - tasks        = ");
-_putd(tasks);
-_puts("\n");
-_puts(" - curr_task_id = ");
-_putd( curr_task_id );
-_puts("\n");
-_puts(" - next_task_id = ");
-_putd(next_task_id);
-_puts("\n");
-_tty_release_lock(  0 );
+unsigned int x = cluster_xy >> Y_WIDTH;
+unsigned int y = cluster_xy & ((1<<Y_WIDTH)-1);
+
+_printf("\n[TASK SWITCH] (%d) -> (%d) on processor[%d,%d,%d] at cycle %d\n",
+        curr_task_id, next_task_id, x, y , lpid, _get_proctime() );
 #endif
 
+    if (curr_task_id != next_task_id)  // actual task switch required
+    {
         unsigned int* curr_ctx_vaddr = &(psched->context[curr_task_id][0]);
         unsigned int* next_ctx_vaddr = &(psched->context[next_task_id][0]);
-        unsigned int procid = _get_procid();
-        unsigned int local_id = procid % NB_PROCS_MAX;
-        unsigned int cluster_id = procid / NB_PROCS_MAX;
 
-        // reset timer counter
+        // reset timer counter. In each cluster,
+        // the NB_PROCS_MAX timers are system timers (TICK)
+
 #if USE_XICU
-        _xcu_timer_reset_cpt(cluster_id, NB_PROCS_MAX + local_id);
+        _xcu_timer_reset_cpt( cluster_xy, lpid );
 #else
-        _timer_reset_cpt(cluster_id, NB_PROCS_MAX + local_id); 
+        _timer_reset_cpt( cluster_xy, lpid); 
 #endif
 
@@ -153 +102 @@
 void _idle_task() 
 {
-    unsigned int count = GIET_IDLE_TASK_PERIOD;
     while(1)
     {
-#if GIET_IDLE_TASK_VERBOSITY == 1
-        _tty_get_lock( 0 );
-        _puts("\n[GIET WARNING] Processor ");
-        _putd(_get_procid());
-        _puts(" idle at cycle ");
-        _putd(_get_proctime());
-        _puts("\n");
-        _tty_release_lock( 0 );
-#endif
+        unsigned int count = GIET_IDLE_TASK_PERIOD;
 
+        // decounting loop
         asm volatile(
                 "move   $3,   %0              \n"
@@ -176 +117 @@
                 : "$3" ); 
 
-         count = GIET_IDLE_TASK_PERIOD;
+        // warning message
+        unsigned int gpid       = _get_procid();
+        unsigned int cluster_xy = gpid / NB_PROCS_MAX;
+        unsigned int lpid       = gpid % NB_PROCS_MAX;
+        unsigned int x          = cluster_xy >> Y_WIDTH;
+        unsigned int y          = cluster_xy & ((1<<Y_WIDTH)-1);
+
+        _printf("\n[GIET WARNING] Processor[%d,%d,%d] still idle at cycle %d\n",
+                x, y, lpid, _get_proctime() );
+
     }
 } // end ctx_idle()
@@ -182 +132 @@
 
 /////////////////////////////////////////////////////////////////////////////////
-// The address of this functionis used to initialise the return address
+// The address of this function is used to initialise the return address
 // in the "idle" task context.
 /////////////////////////////////////////////////////////////////////////////////