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kernel: Give longer time slice to lower priority threads

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This commit is contained in:
Pawel Dziepak 2013-10-09 02:25:21 +02:00
parent a2bdd2842f
commit 24dbeeddb2
1 changed files with 32 additions and 2 deletions
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34
src/system/kernel/scheduler/scheduler_simple.cpp
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@ -40,7 +40,7 @@
#endif
const bigtime_t kThreadQuantum = 3000;
const bigtime_t kThreadQuantum = 1000;
// The run queue. Holds the threads ready to run ordered by priority.
@ -342,6 +342,36 @@ simple_quantum_ended(Thread* thread, bool wasPreempted, bool hasYielded)
}
static inline bigtime_t
simple_quantum_linear_interpolation(bigtime_t maxQuantum, bigtime_t minQuantum,
int32 maxPriority, int32 minPriority, int32 priority)
{
ASSERT(priority <= maxPriority);
ASSERT(priority >= minPriority);
bigtime_t result = (maxQuantum - minQuantum) * (priority - minPriority);
result /= maxPriority - minPriority;
return maxQuantum - result;
}
static inline bigtime_t
simple_get_base_quantum(Thread* thread)
{
int32 priority = simple_get_effective_priority(thread);
if (priority >= B_URGENT_DISPLAY_PRIORITY)
return kThreadQuantum;
if (priority > B_NORMAL_PRIORITY) {
return simple_quantum_linear_interpolation(kThreadQuantum * 4,
kThreadQuantum, B_URGENT_DISPLAY_PRIORITY, B_NORMAL_PRIORITY,
priority);
}
return simple_quantum_linear_interpolation(kThreadQuantum * 64,
kThreadQuantum * 4, B_NORMAL_PRIORITY, B_IDLE_PRIORITY, priority);
}
static inline bigtime_t
simple_compute_quantum(Thread* thread)
{
@ -351,7 +381,7 @@ simple_compute_quantum(Thread* thread)
if (schedulerThreadData->time_left != 0)
quantum = schedulerThreadData->time_left;
else
quantum = kThreadQuantum;
quantum = simple_get_base_quantum(thread);
quantum += schedulerThreadData->stolen_time;
schedulerThreadData->stolen_time = 0;