[haiku-commits] r33965 - haiku/trunk/src/system/kernel/scheduler
- From: axeld@xxxxxxxxxxxxxxxx
- To: haiku-commits@xxxxxxxxxxxxx
- Date: Mon, 9 Nov 2009 20:00:42 +0100 (CET)
Author: axeld
Date: 2009-11-09 20:00:42 +0100 (Mon, 09 Nov 2009)
New Revision: 33965
Changeset: http://dev.haiku-os.org/changeset/33965/haiku
Modified:
haiku/trunk/src/system/kernel/scheduler/scheduler_affine.cpp
Log:
* Changed the affine scheduler to have more or less the same characteristics
as the BeOS scheduler. This makes MediaPlayer playback much better, as high
priority threads could lose their quantum to a worker thread twice in a row
with 4% probability before.
* I did not yet change the simple scheduler as well yet; maybe this isn't the
final one either.
Modified: haiku/trunk/src/system/kernel/scheduler/scheduler_affine.cpp
===================================================================
--- haiku/trunk/src/system/kernel/scheduler/scheduler_affine.cpp
2009-11-09 17:41:10 UTC (rev 33964)
+++ haiku/trunk/src/system/kernel/scheduler/scheduler_affine.cpp
2009-11-09 19:00:42 UTC (rev 33965)
@@ -9,6 +9,7 @@
* Distributed under the terms of the NewOS License.
*/
+
/*! The thread scheduler */
@@ -49,6 +50,7 @@
const bigtime_t kMinThreadQuantum = 3000;
const bigtime_t kMaxThreadQuantum = 10000;
+
struct scheduler_thread_data {
scheduler_thread_data(void)
{
@@ -63,7 +65,7 @@
fLastQueue = -1;
memset(fLastThreadQuantums, 0, sizeof(fLastThreadQuantums));
}
-
+
inline void SetQuantum(int32 quantum)
{
fQuantumAverage -= fLastThreadQuantums[fLastQuantumSlot];
@@ -74,7 +76,7 @@
else
fLastQuantumSlot = 0;
}
-
+
inline int32 GetAverageQuantumUsage() const
{
return fQuantumAverage / kMaxTrackingQuantums;
@@ -198,10 +200,13 @@
SMP_MSG_FLAG_ASYNC);
}
}
-
+
return false;
}
+
+/*! Dequeues the thread after the given \a prevThread from the run queue.
+*/
static inline struct thread *
dequeue_from_run_queue(struct thread *prevThread, int32 currentCPU)
{
@@ -219,6 +224,7 @@
return resultThread;
}
+
/*! Looks for a possible thread to grab/run from another CPU.
Note: thread lock must be held when entering this function
*/
@@ -393,17 +399,30 @@
if (nextThread->priority >= B_FIRST_REAL_TIME_PRIORITY)
break;
- // skip normal threads sometimes (roughly 20%)
- if (_rand() > 0x1a00)
+ // find next thread with lower priority
+ struct thread *lowerNextThread = nextThread->queue_next;
+ struct thread *lowerPrevThread = nextThread;
+ int32 priority = nextThread->priority;
+
+ while (lowerNextThread != NULL
+ && priority == lowerNextThread->priority) {
+ lowerPrevThread = lowerNextThread;
+ lowerNextThread = lowerNextThread->queue_next;
+ }
+ if (lowerNextThread == NULL)
break;
- // skip until next lower priority
- int32 priority = nextThread->priority;
- do {
- prevThread = nextThread;
- nextThread = nextThread->queue_next;
- } while (nextThread->queue_next != NULL
- && priority ==
nextThread->queue_next->priority);
+ int32 priorityDiff = priority -
lowerNextThread->priority;
+ if (priorityDiff > 15)
+ break;
+
+ // skip normal threads sometimes
+ // (twice as probable per priority level)
+ if ((_rand() >> (15 - priorityDiff)) != 0)
+ break;
+
+ nextThread = lowerNextThread;
+ prevThread = lowerPrevThread;
}
TRACE(("dequeuing thread %ld from cpu %ld\n", nextThread->id,
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