Changeset aae2869 in mainline

Timestamp:

2023-02-04T16:19:21Z (15 months ago)

Author:

Jiří Zárevúcky <zarevucky.jiri@…>

Branches:

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

Children:

011c79a

Parents:

8addb24a

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2022-08-16 11:03:29)

git-committer:

Jiří Zárevúcky <zarevucky.jiri@…> (2023-02-04 16:19:21)

Message:

Replace THREAD→ticks with CPU→preempt_deadline

This removes a bit of unnecessary locking in clock().

Location:

kernel/generic

Files:

• include/cpu.h (modified) (1 diff)
• include/proc/thread.h (modified) (1 diff)
• src/proc/scheduler.c (modified) (1 diff)
• src/proc/thread.c (modified) (1 diff)
• src/time/clock.c (modified) (1 diff)

kernel/generic/include/cpu.h

@@ -76 +76 @@
         /** Can only be accessed when interrupts are disabled. */
         uint64_t current_clock_tick;
+        uint64_t preempt_deadline;  /* < when should the currently running thread be preempted */
 
         /**

kernel/generic/include/proc/thread.h

@@ -177 +177 @@
         bool uspace;
 
-        /** Ticks before preemption. */
-        uint64_t ticks;
-
         /** Thread accounting. */
         uint64_t ucycles;

kernel/generic/src/proc/scheduler.c

@@ -236 +236 @@
 
                 thread->cpu = CPU;
-                thread->ticks = us2ticks((i + 1) * 10000);
                 thread->priority = i;  /* Correct rq index */
+
+                /* Time allocation in microseconds. */
+                uint64_t time_to_run = (i + 1) * 10000;
+
+                /* This is safe because interrupts are disabled. */
+                CPU->preempt_deadline = CPU->current_clock_tick + us2ticks(time_to_run);
 
                 /*

kernel/generic/src/proc/thread.c

@@ -372 +372 @@
         thread->thread_code = func;
         thread->thread_arg = arg;
-        thread->ticks = -1;
         thread->ucycles = 0;
         thread->kcycles = 0;

kernel/generic/src/time/clock.c

@@ -184 +184 @@
 
         if (THREAD) {
-                uint64_t ticks;
-
                 irq_spinlock_lock(&CPU->lock, false);
                 CPU->needs_relink += 1 + missed_clock_ticks;
                 irq_spinlock_unlock(&CPU->lock, false);
 
-                irq_spinlock_lock(&THREAD->lock, false);
-                if ((ticks = THREAD->ticks)) {
-                        if (ticks >= 1 + missed_clock_ticks)
-                                THREAD->ticks -= 1 + missed_clock_ticks;
-                        else
-                                THREAD->ticks = 0;
-                }
-                irq_spinlock_unlock(&THREAD->lock, false);
-
-                if (ticks == 0 && PREEMPTION_ENABLED) {
+                if (current_clock_tick >= CPU->preempt_deadline && PREEMPTION_ENABLED) {
                         scheduler();
 #ifdef CONFIG_UDEBUG