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| author | Ingo Molnar <mingo@elte.hu> | 2007-10-15 17:00:18 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2007-10-15 17:00:18 +0200 |
| commit | da84d96176729fb48a8458561e5d8647103168b8 (patch) | |
| tree | 24c952d956178faa9ac8b5c505513c93a87f4f6b /kernel | |
| parent | e5f32a3856caabe745381279f7f32e3b581b59dc (diff) | |
| download | linux-stable-da84d96176729fb48a8458561e5d8647103168b8.tar.gz linux-stable-da84d96176729fb48a8458561e5d8647103168b8.tar.bz2 linux-stable-da84d96176729fb48a8458561e5d8647103168b8.zip | |
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: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched.c | 27 | ||||
| -rw-r--r-- | kernel/sched_fair.c | 2 | ||||
| -rw-r--r-- | kernel/sysctl.c | 8 |
3 files changed, 37 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 791dd08c692f..089d8b12ab76 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2119,6 +2119,17 @@ static void pull_task(struct rq *src_rq, struct task_struct *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? */ static @@ -2139,6 +2150,22 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu, if (task_running(rq, p)) 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; } diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index cea1fa32b3f4..a17b785d7000 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -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_migration_cost = 500000UL; + /************************************************************** * CFS operations on generic schedulable entities: */ diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 230ca4eb57fe..ec14aa8ac51f 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -277,6 +277,14 @@ static ctl_table kern_table[] = { .mode = 0644, .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 { .ctl_name = CTL_UNNUMBERED, |