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Message-ID: <20091109091001.GF23472@in.ibm.com>
Date: Mon, 9 Nov 2009 14:40:01 +0530
From: Bharata B Rao <bharata@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: Dhaval Giani <dhaval@...ux.vnet.ibm.com>,
Balbir Singh <balbir@...ux.vnet.ibm.com>,
Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
Gautham R Shenoy <ego@...ibm.com>,
Srivatsa Vaddagiri <vatsa@...ibm.com>,
Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
Ingo Molnar <mingo@...e.hu>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Pavel Emelyanov <xemul@...nvz.org>,
Herbert Poetzl <herbert@...hfloor.at>,
Avi Kivity <avi@...hat.com>,
Chris Friesen <cfriesen@...tel.com>,
Paul Menage <menage@...gle.com>,
Mike Waychison <mikew@...gle.com>
Subject: [RFC v3 PATCH 2/7] sched: Bandwidth initialization for fair task
groups
sched: Bandwidth initialization for fair task groups.
From: Bharata B Rao <bharata@...ux.vnet.ibm.com>
Introduce the notion of hard limiting for CFS groups by bringing in
the concept of runtime and period for them. Add cgroup files to control
runtime and period.
Signed-off-by: Bharata B Rao <bharata@...ux.vnet.ibm.com>
---
init/Kconfig | 13 +++
kernel/sched.c | 277 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 290 insertions(+), 0 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index f515864..fea8cbe 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -477,6 +477,19 @@ config CGROUP_SCHED
endchoice
+config CFS_HARD_LIMITS
+ bool "Hard Limits for CFS Group Scheduler"
+ depends on EXPERIMENTAL
+ depends on FAIR_GROUP_SCHED && CGROUP_SCHED
+ default n
+ help
+ This option enables hard limiting of CPU time obtained by
+ a fair task group. Use this if you want to throttle a group of tasks
+ based on its CPU usage. For more details refer to
+ Documentation/scheduler/sched-cfs-hard-limits.txt
+
+ Say N if unsure.
+
menuconfig CGROUPS
boolean "Control Group support"
help
diff --git a/kernel/sched.c b/kernel/sched.c
index 1309e8d..1d46fdc 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -237,6 +237,15 @@ static DEFINE_MUTEX(sched_domains_mutex);
#include <linux/cgroup.h>
+#if defined(CONFIG_FAIR_GROUP_SCHED) && defined(CONFIG_CFS_HARD_LIMITS)
+struct cfs_bandwidth {
+ spinlock_t cfs_runtime_lock;
+ ktime_t cfs_period;
+ u64 cfs_runtime;
+ struct hrtimer cfs_period_timer;
+};
+#endif
+
struct cfs_rq;
static LIST_HEAD(task_groups);
@@ -257,6 +266,9 @@ struct task_group {
/* runqueue "owned" by this group on each cpu */
struct cfs_rq **cfs_rq;
unsigned long shares;
+#ifdef CONFIG_CFS_HARD_LIMITS
+ struct cfs_bandwidth cfs_bandwidth;
+#endif
#endif
#ifdef CONFIG_RT_GROUP_SCHED
@@ -445,6 +457,19 @@ struct cfs_rq {
unsigned long rq_weight;
#endif
#endif
+#ifdef CONFIG_CFS_HARD_LIMITS
+ /* set when the group is throttled on this cpu */
+ int cfs_throttled;
+
+ /* runtime currently consumed by the group on this rq */
+ u64 cfs_time;
+
+ /* runtime available to the group on this rq */
+ u64 cfs_runtime;
+
+ /* Protects the cfs runtime related fields of this cfs_rq */
+ spinlock_t cfs_runtime_lock;
+#endif
};
/* Real-Time classes' related field in a runqueue: */
@@ -1833,6 +1858,144 @@ static inline const struct cpumask *sched_bw_period_mask(void)
#endif
+#ifdef CONFIG_FAIR_GROUP_SCHED
+#ifdef CONFIG_CFS_HARD_LIMITS
+
+/*
+ * Runtime allowed for a cfs group before it is hard limited.
+ * default: Infinite which means no hard limiting.
+ */
+u64 sched_cfs_runtime = RUNTIME_INF;
+
+/*
+ * period over which we hard limit the cfs group's bandwidth.
+ * default: 0.5s
+ */
+u64 sched_cfs_period = 500000;
+
+static inline u64 global_cfs_period(void)
+{
+ return sched_cfs_period * NSEC_PER_USEC;
+}
+
+static inline u64 global_cfs_runtime(void)
+{
+ return RUNTIME_INF;
+}
+
+static inline void cfs_rq_runtime_lock(struct cfs_rq *cfs_rq)
+{
+ spin_lock(&cfs_rq->cfs_runtime_lock);
+}
+
+static inline void cfs_rq_runtime_unlock(struct cfs_rq *cfs_rq)
+{
+ spin_unlock(&cfs_rq->cfs_runtime_lock);
+}
+
+/*
+ * Refresh the runtimes of the throttled groups.
+ * But nothing much to do now, will populate this in later patches.
+ */
+static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
+{
+ struct cfs_bandwidth *cfs_b =
+ container_of(timer, struct cfs_bandwidth, cfs_period_timer);
+
+ hrtimer_add_expires_ns(timer, ktime_to_ns(cfs_b->cfs_period));
+ return HRTIMER_RESTART;
+}
+
+/*
+ * TODO: Check if this kind of timer setup is sufficient for cfs or
+ * should we do what rt is doing.
+ */
+static void start_cfs_bandwidth(struct task_group *tg)
+{
+ struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
+
+ /*
+ * Timer isn't setup for groups with infinite runtime
+ */
+ if (cfs_b->cfs_runtime == RUNTIME_INF)
+ return;
+
+ if (hrtimer_active(&cfs_b->cfs_period_timer))
+ return;
+
+ hrtimer_start_range_ns(&cfs_b->cfs_period_timer, cfs_b->cfs_period,
+ 0, HRTIMER_MODE_REL);
+}
+
+static void init_cfs_bandwidth(struct task_group *tg)
+{
+ struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
+
+ cfs_b->cfs_period = ns_to_ktime(global_cfs_period());
+ cfs_b->cfs_runtime = global_cfs_runtime();
+
+ spin_lock_init(&cfs_b->cfs_runtime_lock);
+
+ hrtimer_init(&cfs_b->cfs_period_timer,
+ CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ cfs_b->cfs_period_timer.function = &sched_cfs_period_timer;
+}
+
+static inline void destroy_cfs_bandwidth(struct task_group *tg)
+{
+ hrtimer_cancel(&tg->cfs_bandwidth.cfs_period_timer);
+}
+
+static void init_cfs_hard_limits(struct cfs_rq *cfs_rq, struct task_group *tg)
+{
+ cfs_rq->cfs_time = 0;
+ cfs_rq->cfs_throttled = 0;
+ cfs_rq->cfs_runtime = tg->cfs_bandwidth.cfs_runtime;
+ spin_lock_init(&cfs_rq->cfs_runtime_lock);
+}
+
+#else /* !CONFIG_CFS_HARD_LIMITS */
+
+static void init_cfs_bandwidth(struct task_group *tg)
+{
+ return;
+}
+
+static inline void destroy_cfs_bandwidth(struct task_group *tg)
+{
+ return;
+}
+
+static void init_cfs_hard_limits(struct cfs_rq *cfs_rq, struct task_group *tg)
+{
+ return;
+}
+
+static inline void cfs_rq_runtime_lock(struct cfs_rq *cfs_rq)
+{
+ return;
+}
+
+static inline void cfs_rq_runtime_unlock(struct cfs_rq *cfs_rq)
+{
+ return;
+}
+
+#endif /* CONFIG_CFS_HARD_LIMITS */
+#else /* !CONFIG_FAIR_GROUP_SCHED */
+
+static inline void cfs_rq_runtime_lock(struct cfs_rq *cfs_rq)
+{
+ return;
+}
+
+static inline void cfs_rq_runtime_unlock(struct cfs_rq *cfs_rq)
+{
+ return;
+}
+
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+
#include "sched_stats.h"
#include "sched_idletask.c"
#include "sched_fair.c"
@@ -9286,6 +9449,7 @@ static void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
struct rq *rq = cpu_rq(cpu);
tg->cfs_rq[cpu] = cfs_rq;
init_cfs_rq(cfs_rq, rq);
+ init_cfs_hard_limits(cfs_rq, tg);
cfs_rq->tg = tg;
if (add)
list_add(&cfs_rq->leaf_cfs_rq_list, &rq->leaf_cfs_rq_list);
@@ -9415,6 +9579,10 @@ void __init sched_init(void)
#endif /* CONFIG_USER_SCHED */
#endif /* CONFIG_RT_GROUP_SCHED */
+#ifdef CONFIG_FAIR_GROUP_SCHED
+ init_cfs_bandwidth(&init_task_group);
+#endif
+
#ifdef CONFIG_GROUP_SCHED
list_add(&init_task_group.list, &task_groups);
INIT_LIST_HEAD(&init_task_group.children);
@@ -9441,6 +9609,7 @@ void __init sched_init(void)
init_cfs_rq(&rq->cfs, rq);
init_rt_rq(&rq->rt, rq);
#ifdef CONFIG_FAIR_GROUP_SCHED
+ init_cfs_hard_limits(&rq->cfs, &init_task_group);
init_task_group.shares = init_task_group_load;
INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
#ifdef CONFIG_CGROUP_SCHED
@@ -9716,6 +9885,7 @@ static void free_fair_sched_group(struct task_group *tg)
{
int i;
+ destroy_cfs_bandwidth(tg);
for_each_possible_cpu(i) {
if (tg->cfs_rq)
kfree(tg->cfs_rq[i]);
@@ -9742,6 +9912,7 @@ int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
if (!tg->se)
goto err;
+ init_cfs_bandwidth(tg);
tg->shares = NICE_0_LOAD;
for_each_possible_cpu(i) {
@@ -10465,6 +10636,100 @@ static u64 cpu_shares_read_u64(struct cgroup *cgrp, struct cftype *cft)
return (u64) tg->shares;
}
+
+#ifdef CONFIG_CFS_HARD_LIMITS
+
+static int tg_set_cfs_bandwidth(struct task_group *tg,
+ u64 cfs_period, u64 cfs_runtime)
+{
+ int i;
+
+ spin_lock_irq(&tg->cfs_bandwidth.cfs_runtime_lock);
+ tg->cfs_bandwidth.cfs_period = ns_to_ktime(cfs_period);
+ tg->cfs_bandwidth.cfs_runtime = cfs_runtime;
+
+ for_each_possible_cpu(i) {
+ struct cfs_rq *cfs_rq = tg->cfs_rq[i];
+
+ cfs_rq_runtime_lock(cfs_rq);
+ cfs_rq->cfs_runtime = cfs_runtime;
+ cfs_rq_runtime_unlock(cfs_rq);
+ }
+
+ start_cfs_bandwidth(tg);
+ spin_unlock_irq(&tg->cfs_bandwidth.cfs_runtime_lock);
+ return 0;
+}
+
+int tg_set_cfs_runtime(struct task_group *tg, long cfs_runtime_us)
+{
+ u64 cfs_runtime, cfs_period;
+
+ cfs_period = ktime_to_ns(tg->cfs_bandwidth.cfs_period);
+ cfs_runtime = (u64)cfs_runtime_us * NSEC_PER_USEC;
+ if (cfs_runtime_us < 0)
+ cfs_runtime = RUNTIME_INF;
+
+ return tg_set_cfs_bandwidth(tg, cfs_period, cfs_runtime);
+}
+
+long tg_get_cfs_runtime(struct task_group *tg)
+{
+ u64 cfs_runtime_us;
+
+ if (tg->cfs_bandwidth.cfs_runtime == RUNTIME_INF)
+ return -1;
+
+ cfs_runtime_us = tg->cfs_bandwidth.cfs_runtime;
+ do_div(cfs_runtime_us, NSEC_PER_USEC);
+ return cfs_runtime_us;
+}
+
+int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
+{
+ u64 cfs_runtime, cfs_period;
+
+ cfs_period = (u64)cfs_period_us * NSEC_PER_USEC;
+ cfs_runtime = tg->cfs_bandwidth.cfs_runtime;
+
+ if (cfs_period == 0)
+ return -EINVAL;
+
+ return tg_set_cfs_bandwidth(tg, cfs_period, cfs_runtime);
+}
+
+long tg_get_cfs_period(struct task_group *tg)
+{
+ u64 cfs_period_us;
+
+ cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.cfs_period);
+ do_div(cfs_period_us, NSEC_PER_USEC);
+ return cfs_period_us;
+}
+
+static s64 cpu_cfs_runtime_read_s64(struct cgroup *cgrp, struct cftype *cft)
+{
+ return tg_get_cfs_runtime(cgroup_tg(cgrp));
+}
+
+static int cpu_cfs_runtime_write_s64(struct cgroup *cgrp, struct cftype *cftype,
+ s64 cfs_runtime_us)
+{
+ return tg_set_cfs_runtime(cgroup_tg(cgrp), cfs_runtime_us);
+}
+
+static u64 cpu_cfs_period_read_u64(struct cgroup *cgrp, struct cftype *cft)
+{
+ return tg_get_cfs_period(cgroup_tg(cgrp));
+}
+
+static int cpu_cfs_period_write_u64(struct cgroup *cgrp, struct cftype *cftype,
+ u64 cfs_period_us)
+{
+ return tg_set_cfs_period(cgroup_tg(cgrp), cfs_period_us);
+}
+
+#endif /* CONFIG_CFS_HARD_LIMITS */
#endif /* CONFIG_FAIR_GROUP_SCHED */
#ifdef CONFIG_RT_GROUP_SCHED
@@ -10498,6 +10763,18 @@ static struct cftype cpu_files[] = {
.read_u64 = cpu_shares_read_u64,
.write_u64 = cpu_shares_write_u64,
},
+#ifdef CONFIG_CFS_HARD_LIMITS
+ {
+ .name = "cfs_runtime_us",
+ .read_s64 = cpu_cfs_runtime_read_s64,
+ .write_s64 = cpu_cfs_runtime_write_s64,
+ },
+ {
+ .name = "cfs_period_us",
+ .read_u64 = cpu_cfs_period_read_u64,
+ .write_u64 = cpu_cfs_period_write_u64,
+ },
+#endif /* CONFIG_CFS_HARD_LIMITS */
#endif
#ifdef CONFIG_RT_GROUP_SCHED
{
--
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