diff options
Diffstat (limited to 'kernel/sched.c')
| -rw-r--r-- | kernel/sched.c | 141 |
1 files changed, 111 insertions, 30 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index cecaea67ae9b..85a5fbff2b00 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -176,7 +176,7 @@ struct task_group { struct sched_rt_entity **rt_se; struct rt_rq **rt_rq; - unsigned int rt_ratio; + u64 rt_runtime; /* * shares assigned to a task group governs how much of cpu bandwidth @@ -642,19 +642,21 @@ const_debug unsigned int sysctl_sched_features = const_debug unsigned int sysctl_sched_nr_migrate = 32; /* - * period over which we measure -rt task cpu usage in ms. + * period over which we measure -rt task cpu usage in us. * default: 1s */ -const_debug unsigned int sysctl_sched_rt_period = 1000; +unsigned int sysctl_sched_rt_period = 1000000; -#define SCHED_RT_FRAC_SHIFT 16 -#define SCHED_RT_FRAC (1UL << SCHED_RT_FRAC_SHIFT) +/* + * part of the period that we allow rt tasks to run in us. + * default: 0.95s + */ +int sysctl_sched_rt_runtime = 950000; /* - * ratio of time -rt tasks may consume. - * default: 95% + * single value that denotes runtime == period, ie unlimited time. */ -const_debug unsigned int sysctl_sched_rt_ratio = 62259; +#define RUNTIME_INF ((u64)~0ULL) /* * For kernel-internal use: high-speed (but slightly incorrect) per-cpu @@ -7187,7 +7189,8 @@ void __init sched_init(void) &per_cpu(init_cfs_rq, i), &per_cpu(init_sched_entity, i), i, 1); - init_task_group.rt_ratio = sysctl_sched_rt_ratio; /* XXX */ + init_task_group.rt_runtime = + sysctl_sched_rt_runtime * NSEC_PER_USEC; INIT_LIST_HEAD(&rq->leaf_rt_rq_list); init_tg_rt_entry(rq, &init_task_group, &per_cpu(init_rt_rq, i), @@ -7583,7 +7586,7 @@ struct task_group *sched_create_group(void) goto err; tg->shares = NICE_0_LOAD; - tg->rt_ratio = 0; /* XXX */ + tg->rt_runtime = 0; for_each_possible_cpu(i) { rq = cpu_rq(i); @@ -7785,30 +7788,76 @@ unsigned long sched_group_shares(struct task_group *tg) } /* - * Ensure the total rt_ratio <= sysctl_sched_rt_ratio + * Ensure that the real time constraints are schedulable. */ -int sched_group_set_rt_ratio(struct task_group *tg, unsigned long rt_ratio) +static DEFINE_MUTEX(rt_constraints_mutex); + +static unsigned long to_ratio(u64 period, u64 runtime) +{ + if (runtime == RUNTIME_INF) + return 1ULL << 16; + + runtime *= (1ULL << 16); + div64_64(runtime, period); + return runtime; +} + +static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime) { struct task_group *tgi; unsigned long total = 0; + unsigned long global_ratio = + to_ratio(sysctl_sched_rt_period, + sysctl_sched_rt_runtime < 0 ? + RUNTIME_INF : sysctl_sched_rt_runtime); rcu_read_lock(); - list_for_each_entry_rcu(tgi, &task_groups, list) - total += tgi->rt_ratio; - rcu_read_unlock(); + list_for_each_entry_rcu(tgi, &task_groups, list) { + if (tgi == tg) + continue; - if (total + rt_ratio - tg->rt_ratio > sysctl_sched_rt_ratio) - return -EINVAL; + total += to_ratio(period, tgi->rt_runtime); + } + rcu_read_unlock(); - tg->rt_ratio = rt_ratio; - return 0; + return total + to_ratio(period, runtime) < global_ratio; } -unsigned long sched_group_rt_ratio(struct task_group *tg) +int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us) { - return tg->rt_ratio; + u64 rt_runtime, rt_period; + int err = 0; + + rt_period = sysctl_sched_rt_period * NSEC_PER_USEC; + rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC; + if (rt_runtime_us == -1) + rt_runtime = rt_period; + + mutex_lock(&rt_constraints_mutex); + if (!__rt_schedulable(tg, rt_period, rt_runtime)) { + err = -EINVAL; + goto unlock; + } + if (rt_runtime_us == -1) + rt_runtime = RUNTIME_INF; + tg->rt_runtime = rt_runtime; + unlock: + mutex_unlock(&rt_constraints_mutex); + + return err; } +long sched_group_rt_runtime(struct task_group *tg) +{ + u64 rt_runtime_us; + + if (tg->rt_runtime == RUNTIME_INF) + return -1; + + rt_runtime_us = tg->rt_runtime; + do_div(rt_runtime_us, NSEC_PER_USEC); + return rt_runtime_us; +} #endif /* CONFIG_FAIR_GROUP_SCHED */ #ifdef CONFIG_FAIR_CGROUP_SCHED @@ -7884,17 +7933,49 @@ static u64 cpu_shares_read_uint(struct cgroup *cgrp, struct cftype *cft) return (u64) tg->shares; } -static int cpu_rt_ratio_write_uint(struct cgroup *cgrp, struct cftype *cftype, - u64 rt_ratio_val) +static int cpu_rt_runtime_write(struct cgroup *cgrp, struct cftype *cft, + struct file *file, + const char __user *userbuf, + size_t nbytes, loff_t *unused_ppos) { - return sched_group_set_rt_ratio(cgroup_tg(cgrp), rt_ratio_val); + char buffer[64]; + int retval = 0; + s64 val; + char *end; + + if (!nbytes) + return -EINVAL; + if (nbytes >= sizeof(buffer)) + return -E2BIG; + if (copy_from_user(buffer, userbuf, nbytes)) + return -EFAULT; + + buffer[nbytes] = 0; /* nul-terminate */ + + /* strip newline if necessary */ + if (nbytes && (buffer[nbytes-1] == '\n')) + buffer[nbytes-1] = 0; + val = simple_strtoll(buffer, &end, 0); + if (*end) + return -EINVAL; + + /* Pass to subsystem */ + retval = sched_group_set_rt_runtime(cgroup_tg(cgrp), val); + if (!retval) + retval = nbytes; + return retval; } -static u64 cpu_rt_ratio_read_uint(struct cgroup *cgrp, struct cftype *cft) +static ssize_t cpu_rt_runtime_read(struct cgroup *cgrp, struct cftype *cft, + struct file *file, + char __user *buf, size_t nbytes, + loff_t *ppos) { - struct task_group *tg = cgroup_tg(cgrp); + char tmp[64]; + long val = sched_group_rt_runtime(cgroup_tg(cgrp)); + int len = sprintf(tmp, "%ld\n", val); - return (u64) tg->rt_ratio; + return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); } static struct cftype cpu_files[] = { @@ -7904,9 +7985,9 @@ static struct cftype cpu_files[] = { .write_uint = cpu_shares_write_uint, }, { - .name = "rt_ratio", - .read_uint = cpu_rt_ratio_read_uint, - .write_uint = cpu_rt_ratio_write_uint, + .name = "rt_runtime_us", + .read = cpu_rt_runtime_read, + .write = cpu_rt_runtime_write, }, }; |