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- Rename SCHED_PRI_NTHRESH to SCHED_SLICE_NTHRESH since it is only used in

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slice assignment.  Add a comment describing what it does.
 - Remove a stale XXX comment, the nice should not impact the interactivity,
   nice adjustments only effect non-interactive tasks in ULE.
 - Don't allow nice -20 tasks to totally starve nice 0 tasks.  Give them at
   least SCHED_SLICE_MIN ticks.  We still allow nice 0 tasks to starve nice
   +20 tasks as intended.
This commit is contained in:
Jeff Roberson 2003-11-02 04:10:15 +00:00
parent 7a0d73f587
commit 7d1a81b4dc
1 changed files with 11 additions and 10 deletions
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21
sys/kern/sched_ule.c
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@ -140,7 +140,6 @@ struct td_sched *thread0_sched = &td_sched;
#define SCHED_PRI_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1)
#define SCHED_PRI_NRESV ((PRIO_MAX - PRIO_MIN) + 1)
#define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2)
#define SCHED_PRI_NTHRESH (SCHED_PRI_NHALF - 1)
#define SCHED_PRI_BASE (PRI_MIN_TIMESHARE)
#define SCHED_PRI_INTERACT(score) \
((score) * SCHED_PRI_RANGE / SCHED_INTERACT_MAX)
@ -169,19 +168,19 @@ struct td_sched *thread0_sched = &td_sched;
* SLICE_RANGE: Range of available time slices scaled by hz.
* SLICE_SCALE: The number slices granted per val in the range of [0, max].
* SLICE_NICE: Determine the amount of slice granted to a scaled nice.
* SLICE_NTHRESH: The nice cutoff point for slice assignment.
*/
#define SCHED_SLICE_MIN (slice_min)
#define SCHED_SLICE_MAX (slice_max)
#define SCHED_SLICE_NTHRESH (SCHED_PRI_NHALF - 1)
#define SCHED_SLICE_RANGE (SCHED_SLICE_MAX - SCHED_SLICE_MIN + 1)
#define SCHED_SLICE_SCALE(val, max) (((val) * SCHED_SLICE_RANGE) / (max))
#define SCHED_SLICE_NICE(nice) \
(SCHED_SLICE_MAX - SCHED_SLICE_SCALE((nice), SCHED_PRI_NTHRESH))
(SCHED_SLICE_MAX - SCHED_SLICE_SCALE((nice), SCHED_SLICE_NTHRESH))
/*
* This macro determines whether or not the kse belongs on the current or
* next run queue.
*
* XXX nice value should effect how interactive a kg is.
*/
#define SCHED_INTERACTIVE(kg) \
(sched_interact_score(kg) < SCHED_INTERACT_THRESH)
@ -764,12 +763,12 @@ sched_slice(struct kse *ke)
* nice kse on the run queue. Slice size is determined by
* the kse distance from the last nice ksegrp.
*
* If you are outside of the window you will get no slice and
* you will be reevaluated each time you are selected on the
* run queue.
*
* If the kse is outside of the window it will get no slice
* and will be reevaluated each time it is selected on the
* run queue. The exception to this is nice 0 ksegs when
* a nice -20 is running. They are always granted a minimum
* slice.
*/
if (!SCHED_INTERACTIVE(kg)) {
int nice;
@ -777,8 +776,10 @@ sched_slice(struct kse *ke)
if (kseq->ksq_loads[PRI_TIMESHARE] == 0 ||
kg->kg_nice < kseq->ksq_nicemin)
ke->ke_slice = SCHED_SLICE_MAX;
else if (nice <= SCHED_PRI_NTHRESH)
else if (nice <= SCHED_SLICE_NTHRESH)
ke->ke_slice = SCHED_SLICE_NICE(nice);
else if (kg->kg_nice == 0)
ke->ke_slice = SCHED_SLICE_MIN;
else
ke->ke_slice = 0;
} else