Author: avg
Date: Mon Dec 19 20:01:21 2011
New Revision: 228718
URL: http://svn.freebsd.org/changeset/base/228718
Log:
ule: ensure that batch timeshare threads are scheduled fairly
With the previous code, if the range of priorities for timeshare batch
threads was greater than RQ_NQS, then the threads with low priorities in
the part of the range above RQ_NQS would be scheduled to the run-queues
as if they had high priorities at the beginning of the range.
In other words, threads with a nice level of +N could be scheduled as
if they had a nice level of -M.
Reported by: George Mitchell <geo...@m5p.com>
Reviewed by: jhb
Tested by: George Mitchell <geo...@m5p.com> (earlier version)
MFC after: 1 week
Modified:
head/sys/kern/sched_ule.c
Modified: head/sys/kern/sched_ule.c
==============================================================================
--- head/sys/kern/sched_ule.c Mon Dec 19 19:02:36 2011 (r228717)
+++ head/sys/kern/sched_ule.c Mon Dec 19 20:01:21 2011 (r228718)
@@ -125,6 +125,7 @@ static struct td_sched td_sched0;
*/
#define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE
+ 1)
#define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE -
SCHED_PRI_NRESV) / 2)
+#define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE -
PRI_INTERACT_RANGE)
#define PRI_MIN_INTERACT PRI_MIN_TIMESHARE
#define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE
- 1)
@@ -416,7 +417,6 @@ sched_shouldpreempt(int pri, int cpri, i
return (0);
}
-#define TS_RQ_PPQ (((PRI_MAX_BATCH - PRI_MIN_BATCH) + 1) / RQ_NQS)
/*
* Add a thread to the actual run-queue. Keeps transferable counts up to
* date with what is actually on the run-queue. Selects the correct
@@ -449,7 +449,7 @@ tdq_runq_add(struct tdq *tdq, struct thr
* realtime. Use the whole queue to represent these values.
*/
if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) {
- pri = (pri - PRI_MIN_BATCH) / TS_RQ_PPQ;
+ pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE;
pri = (pri + tdq->tdq_idx) % RQ_NQS;
/*
* This effectively shortens the queue by one so we
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