+}
+
+/*
+ * Define shifts for simulating (5/8) ** n
+ *
+ * Shift structures for holding update shifts. Actual computation
+ * is usage = (usage >> shift1) +/- (usage >> abs(shift2)) where the
+ * +/- is determined by the sign of shift 2.
+ */
+struct shift_data {
+ int shift1;
+ int shift2;
+};
+
+#define SCHED_DECAY_TICKS 32
+static struct shift_data sched_decay_shifts[SCHED_DECAY_TICKS] = {
+ {1,1},{1,3},{1,-3},{2,-7},{3,5},{3,-5},{4,-8},{5,7},
+ {5,-7},{6,-10},{7,10},{7,-9},{8,-11},{9,12},{9,-11},{10,-13},
+ {11,14},{11,-13},{12,-15},{13,17},{13,-15},{14,-17},{15,19},{16,18},
+ {16,-19},{17,22},{18,20},{18,-20},{19,26},{20,22},{20,-22},{21,-27}
+};
+
+/*
+ * do_priority_computation:
+ *
+ * Calculate the timesharing priority based upon usage and load.
+ */
+#define do_priority_computation(thread, pri) \
+ MACRO_BEGIN \
+ (pri) = (thread)->priority /* start with base priority */ \
+ - ((thread)->sched_usage >> (thread)->pri_shift); \
+ if ((pri) < MINPRI_USER) \
+ (pri) = MINPRI_USER; \
+ else \
+ if ((pri) > MAXPRI_KERNEL) \
+ (pri) = MAXPRI_KERNEL; \
+ MACRO_END
+
+/*
+ * set_priority:
+ *
+ * Set the base priority of the thread
+ * and reset its scheduled priority.
+ *
+ * Called with the thread locked.
+ */
+void
+set_priority(
+ register thread_t thread,
+ register int priority)
+{
+ thread->priority = priority;
+ compute_priority(thread, FALSE);
+}
+
+/*
+ * compute_priority:
+ *
+ * Reset the scheduled priority of the thread
+ * according to its base priority if the
+ * thread has not been promoted or depressed.
+ *
+ * Called with the thread locked.
+ */
+void
+compute_priority(
+ register thread_t thread,
+ boolean_t override_depress)
+{
+ register int priority;
+
+ if ( !(thread->sched_mode & TH_MODE_PROMOTED) &&
+ (!(thread->sched_mode & TH_MODE_ISDEPRESSED) ||
+ override_depress ) ) {
+ if (thread->sched_mode & TH_MODE_TIMESHARE)
+ do_priority_computation(thread, priority);
+ else
+ priority = thread->priority;
+
+ set_sched_pri(thread, priority);
+ }
+}
+
+/*
+ * compute_my_priority:
+ *
+ * Reset the scheduled priority for
+ * a timesharing thread.
+ *
+ * Only for use on the current thread
+ * if timesharing and not depressed.
+ *
+ * Called with the thread locked.
+ */
+void
+compute_my_priority(
+ register thread_t thread)
+{
+ register int priority;
+
+ do_priority_computation(thread, priority);
+ assert(thread->runq == PROCESSOR_NULL);
+ thread->sched_pri = priority;
+}
+
+/*
+ * update_priority
+ *
+ * Perform housekeeping operations driven by scheduler tick.
+ *
+ * Called with the thread locked.
+ */
+void
+update_priority(
+ register thread_t thread)
+{
+ register unsigned ticks;
+ register uint32_t delta;
+
+ ticks = sched_tick - thread->sched_stamp;
+ assert(ticks != 0);
+ thread->sched_stamp += ticks;
+ thread->pri_shift = sched_pri_shift;
+
+ /*
+ * Gather cpu usage data.
+ */
+ thread_timer_delta(thread, delta);
+ if (ticks < SCHED_DECAY_TICKS) {
+ register struct shift_data *shiftp;
+
+ /*
+ * Accumulate timesharing usage only
+ * during contention for processor
+ * resources.
+ */
+ if (thread->pri_shift < INT8_MAX)
+ thread->sched_usage += delta;
+
+ thread->cpu_usage += delta + thread->cpu_delta;
+ thread->cpu_delta = 0;
+
+ shiftp = &sched_decay_shifts[ticks];
+ if (shiftp->shift2 > 0) {
+ thread->cpu_usage =
+ (thread->cpu_usage >> shiftp->shift1) +
+ (thread->cpu_usage >> shiftp->shift2);
+ thread->sched_usage =
+ (thread->sched_usage >> shiftp->shift1) +
+ (thread->sched_usage >> shiftp->shift2);
+ }
+ else {
+ thread->cpu_usage =
+ (thread->cpu_usage >> shiftp->shift1) -
+ (thread->cpu_usage >> -(shiftp->shift2));
+ thread->sched_usage =
+ (thread->sched_usage >> shiftp->shift1) -
+ (thread->sched_usage >> -(shiftp->shift2));
+ }
+ }
+ else {
+ thread->cpu_usage = thread->cpu_delta = 0;
+ thread->sched_usage = 0;
+ }
projects / apple / xnu.git / blobdiff