Commit da84d961 authored by Ingo Molnar's avatar Ingo Molnar

sched: reintroduce cache-hot affinity

reintroduce a simplified version of cache-hot/cold scheduling
affinity. This improves performance with certain SMP workloads,
such as sysbench.
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e5f32a38
...@@ -1415,6 +1415,7 @@ extern unsigned int sysctl_sched_wakeup_granularity; ...@@ -1415,6 +1415,7 @@ extern unsigned int sysctl_sched_wakeup_granularity;
extern unsigned int sysctl_sched_batch_wakeup_granularity; extern unsigned int sysctl_sched_batch_wakeup_granularity;
extern unsigned int sysctl_sched_child_runs_first; extern unsigned int sysctl_sched_child_runs_first;
extern unsigned int sysctl_sched_features; extern unsigned int sysctl_sched_features;
extern unsigned int sysctl_sched_migration_cost;
#endif #endif
extern unsigned int sysctl_sched_compat_yield; extern unsigned int sysctl_sched_compat_yield;
......
...@@ -2118,6 +2118,17 @@ static void pull_task(struct rq *src_rq, struct task_struct *p, ...@@ -2118,6 +2118,17 @@ static void pull_task(struct rq *src_rq, struct task_struct *p,
check_preempt_curr(this_rq, p); check_preempt_curr(this_rq, p);
} }
/*
* Is this task likely cache-hot:
*/
static inline int
task_hot(struct task_struct *p, unsigned long long now, struct sched_domain *sd)
{
s64 delta = now - p->se.exec_start;
return delta < (long long)sysctl_sched_migration_cost;
}
/* /*
* can_migrate_task - may task p from runqueue rq be migrated to this_cpu? * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
*/ */
...@@ -2139,6 +2150,22 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu, ...@@ -2139,6 +2150,22 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
if (task_running(rq, p)) if (task_running(rq, p))
return 0; return 0;
/*
* Aggressive migration if:
* 1) task is cache cold, or
* 2) too many balance attempts have failed.
*/
if (sd->nr_balance_failed > sd->cache_nice_tries) {
#ifdef CONFIG_SCHEDSTATS
if (task_hot(p, rq->clock, sd))
schedstat_inc(sd, lb_hot_gained[idle]);
#endif
return 1;
}
if (task_hot(p, rq->clock, sd))
return 0;
return 1; return 1;
} }
......
...@@ -74,6 +74,8 @@ const_debug unsigned int sysctl_sched_batch_wakeup_granularity = 10000000UL; ...@@ -74,6 +74,8 @@ const_debug unsigned int sysctl_sched_batch_wakeup_granularity = 10000000UL;
*/ */
const_debug unsigned int sysctl_sched_wakeup_granularity = 10000000UL; const_debug unsigned int sysctl_sched_wakeup_granularity = 10000000UL;
const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
/************************************************************** /**************************************************************
* CFS operations on generic schedulable entities: * CFS operations on generic schedulable entities:
*/ */
......
...@@ -277,6 +277,14 @@ static ctl_table kern_table[] = { ...@@ -277,6 +277,14 @@ static ctl_table kern_table[] = {
.mode = 0644, .mode = 0644,
.proc_handler = &proc_dointvec, .proc_handler = &proc_dointvec,
}, },
{
.ctl_name = CTL_UNNUMBERED,
.procname = "sched_migration_cost",
.data = &sysctl_sched_migration_cost,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = &proc_dointvec,
},
#endif #endif
{ {
.ctl_name = CTL_UNNUMBERED, .ctl_name = CTL_UNNUMBERED,
......
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