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sched: cfs, add load-calculation methods

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add the new load-calculation methods of CFS.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2007-07-09 18:51:59 +02:00
parent 14531189f0
commit 45bf76df48
1 changed files with 120 additions and 18 deletions
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138
kernel/sched.c
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@ -671,6 +671,108 @@ static inline void resched_task(struct task_struct *p)
#include "sched_stats.h"
static u64 div64_likely32(u64 divident, unsigned long divisor)
{
#if BITS_PER_LONG == 32
if (likely(divident <= 0xffffffffULL))
return (u32)divident / divisor;
do_div(divident, divisor);
return divident;
#else
return divident / divisor;
#endif
}
#if BITS_PER_LONG == 32
# define WMULT_CONST (~0UL)
#else
# define WMULT_CONST (1UL << 32)
#endif
#define WMULT_SHIFT 32
static inline unsigned long
calc_delta_mine(unsigned long delta_exec, unsigned long weight,
struct load_weight *lw)
{
u64 tmp;
if (unlikely(!lw->inv_weight))
lw->inv_weight = WMULT_CONST / lw->weight;
tmp = (u64)delta_exec * weight;
/*
* Check whether we'd overflow the 64-bit multiplication:
*/
if (unlikely(tmp > WMULT_CONST)) {
tmp = ((tmp >> WMULT_SHIFT/2) * lw->inv_weight)
>> (WMULT_SHIFT/2);
} else {
tmp = (tmp * lw->inv_weight) >> WMULT_SHIFT;
}
return (unsigned long)min(tmp, (u64)sysctl_sched_runtime_limit);
}
static inline unsigned long
calc_delta_fair(unsigned long delta_exec, struct load_weight *lw)
{
return calc_delta_mine(delta_exec, NICE_0_LOAD, lw);
}
static void update_load_add(struct load_weight *lw, unsigned long inc)
{
lw->weight += inc;
lw->inv_weight = 0;
}
static void update_load_sub(struct load_weight *lw, unsigned long dec)
{
lw->weight -= dec;
lw->inv_weight = 0;
}
static void __update_curr_load(struct rq *rq, struct load_stat *ls)
{
if (rq->curr != rq->idle && ls->load.weight) {
ls->delta_exec += ls->delta_stat;
ls->delta_fair += calc_delta_fair(ls->delta_stat, &ls->load);
ls->delta_stat = 0;
}
}
/*
* Update delta_exec, delta_fair fields for rq.
*
* delta_fair clock advances at a rate inversely proportional to
* total load (rq->ls.load.weight) on the runqueue, while
* delta_exec advances at the same rate as wall-clock (provided
* cpu is not idle).
*
* delta_exec / delta_fair is a measure of the (smoothened) load on this
* runqueue over any given interval. This (smoothened) load is used
* during load balance.
*
* This function is called /before/ updating rq->ls.load
* and when switching tasks.
*/
static void update_curr_load(struct rq *rq, u64 now)
{
struct load_stat *ls = &rq->ls;
u64 start;
start = ls->load_update_start;
ls->load_update_start = now;
ls->delta_stat += now - start;
/*
* Stagger updates to ls->delta_fair. Very frequent updates
* can be expensive.
*/
if (ls->delta_stat >= sysctl_sched_stat_granularity)
__update_curr_load(rq, ls);
}
/*
* To aid in avoiding the subversion of "niceness" due to uneven distribution
* of tasks with abnormal "nice" values across CPUs the contribution that
@ -693,24 +795,6 @@ static inline void resched_task(struct task_struct *p)
#define RTPRIO_TO_LOAD_WEIGHT(rp) \
(PRIO_TO_LOAD_WEIGHT(MAX_RT_PRIO) + LOAD_WEIGHT(rp))
static void set_load_weight(struct task_struct *p)
{
if (task_has_rt_policy(p)) {
#ifdef CONFIG_SMP
if (p == task_rq(p)->migration_thread)
/*
* The migration thread does the actual balancing.
* Giving its load any weight will skew balancing
* adversely.
*/
p->load_weight = 0;
else
#endif
p->load_weight = RTPRIO_TO_LOAD_WEIGHT(p->rt_priority);
} else
p->load_weight = PRIO_TO_LOAD_WEIGHT(p->static_prio);
}
static inline void
inc_raw_weighted_load(struct rq *rq, const struct task_struct *p)
{
@ -735,6 +819,24 @@ static inline void dec_nr_running(struct task_struct *p, struct rq *rq)
dec_raw_weighted_load(rq, p);
}
static void set_load_weight(struct task_struct *p)
{
if (task_has_rt_policy(p)) {
#ifdef CONFIG_SMP
if (p == task_rq(p)->migration_thread)
/*
* The migration thread does the actual balancing.
* Giving its load any weight will skew balancing
* adversely.
*/
p->load_weight = 0;
else
#endif
p->load_weight = RTPRIO_TO_LOAD_WEIGHT(p->rt_priority);
} else
p->load_weight = PRIO_TO_LOAD_WEIGHT(p->static_prio);
}
/*
* Adding/removing a task to/from a priority array:
*/