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sched: speed up and simplify vslice calculations

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speed up and simplify vslice calculations.

[ From: Mike Galbraith <efault@gmx.de>: build fix ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2007-10-15 17:00:12 +02:00 committed by Ingo Molnar
parent b0ffd246ea
commit 5f6d858ecc
4 changed files with 14 additions and 14 deletions
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2
include/linux/sched.h
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@ -1400,7 +1400,7 @@ extern void sched_idle_next(void);
#ifdef CONFIG_SCHED_DEBUG
extern unsigned int sysctl_sched_latency;
extern unsigned int sysctl_sched_min_granularity;
extern unsigned int sysctl_sched_nr_latency;
extern unsigned int sysctl_sched_wakeup_granularity;
extern unsigned int sysctl_sched_batch_wakeup_granularity;
extern unsigned int sysctl_sched_child_runs_first;

2
kernel/sched_debug.c
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@ -210,7 +210,7 @@ static int sched_debug_show(struct seq_file *m, void *v)
#define PN(x) \
SEQ_printf(m, " .%-40s: %Ld.%06ld\n", #x, SPLIT_NS(x))
PN(sysctl_sched_latency);
PN(sysctl_sched_min_granularity);
PN(sysctl_sched_nr_latency);
PN(sysctl_sched_wakeup_granularity);
PN(sysctl_sched_batch_wakeup_granularity);
PN(sysctl_sched_child_runs_first);

15
kernel/sched_fair.c
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@ -46,7 +46,7 @@ const_debug unsigned int sysctl_sched_child_runs_first = 1;
* Minimal preemption granularity for CPU-bound tasks:
* (default: 2 msec, units: nanoseconds)
*/
unsigned int sysctl_sched_min_granularity __read_mostly = 2000000ULL;
const_debug unsigned int sysctl_sched_nr_latency = 20;
/*
* sys_sched_yield() compat mode
@ -222,8 +222,7 @@ static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
static u64 __sched_period(unsigned long nr_running)
{
u64 period = sysctl_sched_latency;
unsigned long nr_latency =
sysctl_sched_latency / sysctl_sched_min_granularity;
unsigned long nr_latency = sysctl_sched_nr_latency;
if (unlikely(nr_running > nr_latency)) {
period *= nr_running;
@ -245,11 +244,15 @@ static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
static u64 __sched_vslice(unsigned long nr_running)
{
u64 period = __sched_period(nr_running);
unsigned long period = sysctl_sched_latency;
unsigned long nr_latency = sysctl_sched_nr_latency;
do_div(period, nr_running);
if (unlikely(nr_running > nr_latency))
nr_running = nr_latency;
return period;
period /= nr_running;
return (u64)period;
}
/*

9
kernel/sysctl.c
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@ -222,14 +222,11 @@ static ctl_table kern_table[] = {
#ifdef CONFIG_SCHED_DEBUG
{
.ctl_name = CTL_UNNUMBERED,
.procname = "sched_min_granularity_ns",
.data = &sysctl_sched_min_granularity,
.procname = "sched_nr_latency",
.data = &sysctl_sched_nr_latency,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &min_sched_granularity_ns,
.extra2 = &max_sched_granularity_ns,
.proc_handler = &proc_dointvec,
},
{
.ctl_name = CTL_UNNUMBERED,