Changeset 3260ada in mainline

Timestamp:

2006-02-04T21:08:45Z (19 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

e72b0a3

Parents:

04225a7

Message:

Simplify load balancing activation.
This in fact removes the livelock that prevented cpu_sleep() to be called in SMP systems.

Location:

generic

Files:

• include/cpu.h (modified) (1 diff)
• src/cpu/cpu.c (modified) (1 diff)
• src/proc/scheduler.c (modified) (6 diffs)

generic/include/cpu.h

@@ -58 +58 @@
         link_t timeout_active_head;
 
-        #ifdef CONFIG_SMP
-        atomic_t kcpulbstarted;
-        waitq_t kcpulb_wq;
-        #endif /* CONFIG_SMP */
-
         /**
          * Processor ID assigned by kernel.

generic/src/cpu/cpu.c

@@ -68 +68 @@
                         spinlock_initialize(&cpus[i].lock, "cpu_t.lock");
 
-                        #ifdef CONFIG_SMP
-                        waitq_initialize(&cpus[i].kcpulb_wq);
-                        #endif /* __SMP */
-                        
                         for (j = 0; j < RQ_COUNT; j++) {
                                 spinlock_initialize(&cpus[i].rq[j].lock, "rq_t.lock");

generic/src/proc/scheduler.c

@@ -134 +134 @@
         
         if (n == 0) {
-                #ifdef CONFIG_SMP
-                /*
-                 * If the load balancing thread is not running, wake it up and
-                 * set CPU-private flag that the kcpulb has been started.
-                 */
-                if (test_and_set(&CPU->kcpulbstarted) == 0) {
-                        waitq_wakeup(&CPU->kcpulb_wq, 0);
-                        goto loop;
-                }
-                #endif /* CONFIG_SMP */
-                
                 /*
                  * For there was nothing to run, the CPU goes to sleep
                  * until a hardware interrupt or an IPI comes.
                  * This improves energy saving and hyperthreading.
-                 * On the other hand, several hardware interrupts can be ignored.
                  */
                  cpu_sleep();
@@ -482 +470 @@
 loop:
         /*
-         * Sleep until there's some work to do.
+         * Work in 1s intervals.
          */
-        waitq_sleep(&CPU->kcpulb_wq);
+        thread_sleep(1);
 
 not_satisfied:
@@ -579 +567 @@
                                 spinlock_lock(&t->lock);
                                 #ifdef KCPULB_VERBOSE
-                                printf("kcpulb%d: TID %d -> cpu%d, nrdy=%d, avg=%d\n", CPU->id, t->tid, CPU->id, CPU->nrdy, nrdy / config.cpu_active);
+                                printf("kcpulb%d: TID %d -> cpu%d, nrdy=%d, avg=%d\n", CPU->id, t->tid, CPU->id, CPU->nrdy, atomic_get(&nrdy) / config.cpu_active);
                                 #endif
                                 t->flags |= X_STOLEN;
@@ -607 +595 @@
                  */
                 scheduler();
-        } 
-        else {
+        } else {
                 /*
                  * We failed to migrate a single thread.
-                 * Something more sophisticated should be done.
+                 * Give up this turn.
                  */
-                scheduler();
+                goto loop;
         }
                 
@@ -619 +606 @@
 
 satisfied:
-        /*
-         * Tell find_best_thread() to wake us up later again.
-         */
-        atomic_set(&CPU->kcpulbstarted,0);
         goto loop;
 }
@@ -656 +639 @@
                                 continue;
                         }
-                        printf("Rq %d: ", i);
+                        printf("\tRq %d: ", i);
                         for (cur=r->rq_head.next; cur!=&r->rq_head; cur=cur->next) {
                                 t = list_get_instance(cur, thread_t, rq_link);