iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

sched: vslice fixups for non-0 nice levels

Browse Source 
Make vslice accurate wrt nice levels, and add some comments
while we're at it.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Ingo Molnar 2007-10-15 17:00:13 +02:00
parent 3a25201572
commit 647e7cac2d
1 changed files with 40 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
kernel/sched_fair.c
View File

@ -217,6 +217,15 @@ static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
* Scheduling class statistics methods:
*/
/*
* The idea is to set a period in which each task runs once.
*
* When there are too many tasks (sysctl_sched_nr_latency) we have to stretch
* this period because otherwise the slices get too small.
*
* p = (nr <= nl) ? l : l*nr/nl
*/
static u64 __sched_period(unsigned long nr_running)
{
u64 period = sysctl_sched_latency;
@ -230,27 +239,45 @@ static u64 __sched_period(unsigned long nr_running)
return period;
}
/*
* We calculate the wall-time slice from the period by taking a part
* proportional to the weight.
*
* s = p*w/rw
*/
static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
u64 period = __sched_period(cfs_rq->nr_running);
u64 slice = __sched_period(cfs_rq->nr_running);
period *= se->load.weight;
do_div(period, cfs_rq->load.weight);
slice *= se->load.weight;
do_div(slice, cfs_rq->load.weight);
return period;
return slice;
}
static u64 __sched_vslice(unsigned long nr_running)
/*
* We calculate the vruntime slice.
*
* vs = s/w = p/rw
*/
static u64 __sched_vslice(unsigned long rq_weight, unsigned long nr_running)
{
unsigned long period = sysctl_sched_latency;
unsigned long nr_latency = sysctl_sched_nr_latency;
u64 vslice = __sched_period(nr_running);
if (unlikely(nr_running > nr_latency))
nr_running = nr_latency;
do_div(vslice, rq_weight);
period /= nr_running;
return vslice;
}
return (u64)period;
static u64 sched_vslice(struct cfs_rq *cfs_rq)
{
return __sched_vslice(cfs_rq->load.weight, cfs_rq->nr_running);
}
static u64 sched_vslice_add(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
return __sched_vslice(cfs_rq->load.weight + se->load.weight,
cfs_rq->nr_running + 1);
}
/*
@ -469,10 +496,10 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
vruntime >>= 1;
}
} else if (sched_feat(APPROX_AVG) && cfs_rq->nr_running)
vruntime += __sched_vslice(cfs_rq->nr_running)/2;
vruntime += sched_vslice(cfs_rq)/2;
if (initial && sched_feat(START_DEBIT))
vruntime += __sched_vslice(cfs_rq->nr_running + 1);
vruntime += sched_vslice_add(cfs_rq, se);
if (!initial) {
if (sched_feat(NEW_FAIR_SLEEPERS))