From: Patrick Bellasi <patrick.bellasi@arm.com>
To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>, Tejun Heo <tj@kernel.org>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Paul Turner <pjt@google.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Juri Lelli <juri.lelli@redhat.com>, Todd Kjos <tkjos@google.com>,
Joel Fernandes <joelaf@google.com>,
Steve Muckle <smuckle@google.com>,
Suren Baghdasaryan <surenb@google.com>
Subject: [PATCH v3 10/14] sched/core: uclamp: map TG's clamp values into CPU's clamp groups
Date: Mon, 6 Aug 2018 17:39:42 +0100 [thread overview]
Message-ID: <20180806163946.28380-11-patrick.bellasi@arm.com> (raw)
In-Reply-To: <20180806163946.28380-1-patrick.bellasi@arm.com>
Utilization clamping requires to map each different clamp value
into one of the available clamp groups used by the scheduler's fast-path
to account for RUNNABLE tasks. Thus, each time a TG's clamp value is
updated we need to get a reference to the new value's clamp group and
release a reference to the previous one.
Let's ensure that, whenever a task group is assigned a specific
clamp_value, this is properly translated into a unique clamp group to be
used in the fast-path (i.e. at enqueue/dequeue time).
We do that by slightly refactoring uclamp_group_get() to make the
*task_struct parameter optional. This allows to re-use the code already
available to support the per-task API.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-pm@vger.kernel.org
---
Changes in v3:
Message-ID: <CAJuCfpF6=L=0LrmNnJrTNPazT4dWKqNv+thhN0dwpKCgUzs9sg@mail.gmail.com>
- add explicit calls to uclamp_group_find(), which is now not more
part of uclamp_group_get()
Others:
- rebased on tip/sched/core
Changes in v2:
- rebased on v4.18-rc4
- this code has been split from a previous patch to simplify the review
---
include/linux/sched.h | 2 +
kernel/sched/core.c | 114 ++++++++++++++++++++++++++++++++++++++++--
2 files changed, 111 insertions(+), 5 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3fac2d098084..04f3b47a31bc 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -583,6 +583,8 @@ struct sched_dl_entity {
*
* A utilization clamp group maps a "clamp value" (value), i.e.
* util_{min,max}, to a "clamp group index" (group_id).
+ * The same "group_id" can be used by multiple TG's to enforce the same
+ * clamp "value" for a given clamp index.
*/
struct uclamp_se {
/* Utilization constraint for tasks in this group */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f692df3787bd..01229864fd93 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1205,7 +1205,8 @@ static inline void uclamp_group_get(struct task_struct *p,
raw_spin_unlock_irqrestore(&uc_map[next_group_id].se_lock, flags);
/* Update CPU's clamp group refcounts of RUNNABLE task */
- uclamp_task_update_active(p, clamp_id, next_group_id);
+ if (p)
+ uclamp_task_update_active(p, clamp_id, next_group_id);
/* Release the previous clamp group */
uclamp_group_put(clamp_id, prev_group_id);
@@ -1262,22 +1263,60 @@ static inline int alloc_uclamp_sched_group(struct task_group *tg,
{
struct uclamp_se *uc_se;
int clamp_id;
+ int group_id;
for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id) {
uc_se = &tg->uclamp[clamp_id];
uc_se->value = parent->uclamp[clamp_id].value;
uc_se->group_id = UCLAMP_NOT_VALID;
+
uc_se->effective.value =
parent->uclamp[clamp_id].effective.value;
uc_se->effective.group_id =
parent->uclamp[clamp_id].effective.group_id;
+
+ /*
+ * Find a valid group_id.
+ * Since it's a parent clone this will never fail.
+ */
+ group_id = uclamp_group_find(clamp_id, uc_se->value);
+#ifdef SCHED_DEBUG
+ if (unlikely(group_id == -ENOSPC)) {
+ WARN(1, "invalid clamp group [%d:%d] cloning\n",
+ clamp_id, parent->uclamp[clamp_id].group_id);
+ return 0;
+ }
+#endif
+ uclamp_group_get(NULL, clamp_id, group_id, uc_se,
+ parent->uclamp[clamp_id].value);
}
return 1;
}
+
+/**
+ * release_uclamp_sched_group: release utilization clamp references of a TG
+ * @tg: the task group being removed
+ *
+ * An empty task group can be removed only when it has no more tasks or child
+ * groups. This means that we can also safely release all the reference
+ * counting to clamp groups.
+ */
+static inline void free_uclamp_sched_group(struct task_group *tg)
+{
+ struct uclamp_se *uc_se;
+ int clamp_id;
+
+ for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id) {
+ uc_se = &tg->uclamp[clamp_id];
+ uclamp_group_put(clamp_id, uc_se->group_id);
+ }
+}
+
#else /* CONFIG_UCLAMP_TASK_GROUP */
static inline void init_uclamp_sched_group(void) { }
+static inline void free_uclamp_sched_group(struct task_group *tg) { }
static inline int alloc_uclamp_sched_group(struct task_group *tg,
struct task_group *parent)
{
@@ -1389,6 +1428,7 @@ static void __init init_uclamp(void)
#else /* CONFIG_UCLAMP_TASK */
static inline void uclamp_cpu_get(struct rq *rq, struct task_struct *p) { }
static inline void uclamp_cpu_put(struct rq *rq, struct task_struct *p) { }
+static inline void free_uclamp_sched_group(struct task_group *tg) { }
static inline int alloc_uclamp_sched_group(struct task_group *tg,
struct task_group *parent)
{
@@ -6958,6 +6998,7 @@ static DEFINE_SPINLOCK(task_group_lock);
static void sched_free_group(struct task_group *tg)
{
+ free_uclamp_sched_group(tg);
free_fair_sched_group(tg);
free_rt_sched_group(tg);
autogroup_free(tg);
@@ -7203,8 +7244,36 @@ static void cpu_cgroup_attach(struct cgroup_taskset *tset)
}
#ifdef CONFIG_UCLAMP_TASK_GROUP
+/**
+ * cpu_util_update_hier: propagete effective clamp down the hierarchy
+ * @css: the task group to update
+ * @clamp_id: the clamp index to update
+ * @value: the new task group clamp value
+ * @group_id: the group index mapping the new task clamp value
+ *
+ * The effective clamp for a TG is expected to track the most restrictive
+ * value between the TG's clamp value and it's parent effective clamp value.
+ * This method achieve that:
+ * 1. updating the current TG effective value
+ * 2. walking all the descendant task group that needs an update
+ *
+ * A TG's effective clamp needs to be updated when its current value is not
+ * matching the TG's clamp value. In this case indeed either:
+ * a) the parent has got a more relaxed clamp value
+ * thus potentially we can relax the effective value for this group
+ * b) the parent has got a more strict clamp value
+ * thus potentially we have to restrict the effective value of this group
+ *
+ * Restriction and relaxation of current TG's effective clamp values needs to
+ * be propagated down to all the descendants. When a subgroup is found which
+ * has already its effective clamp value matching its clamp value, then we can
+ * safely skip all its descendants which are granted to be already in sync.
+ *
+ * The TG's group_id is also updated to ensure it tracks the effective clamp
+ * value.
+ */
static void cpu_util_update_hier(struct cgroup_subsys_state *css,
- int clamp_id, int value)
+ int clamp_id, int value, int group_id)
{
struct cgroup_subsys_state *top_css = css;
struct uclamp_se *uc_se, *uc_parent;
@@ -7232,20 +7301,25 @@ static void cpu_util_update_hier(struct cgroup_subsys_state *css,
}
/* Propagate the most restrictive effective value */
- if (uc_parent->effective.value < value)
+ if (uc_parent->effective.value < value) {
value = uc_parent->effective.value;
+ group_id = uc_parent->effective.group_id;
+ }
if (uc_se->effective.value == value)
continue;
uc_se->effective.value = value;
+ uc_se->effective.group_id = group_id;
}
}
static int cpu_util_min_write_u64(struct cgroup_subsys_state *css,
struct cftype *cftype, u64 min_value)
{
+ struct uclamp_se *uc_se;
struct task_group *tg;
int ret = -EINVAL;
+ int group_id;
if (min_value > SCHED_CAPACITY_SCALE)
return -ERANGE;
@@ -7261,8 +7335,22 @@ static int cpu_util_min_write_u64(struct cgroup_subsys_state *css,
if (tg->uclamp[UCLAMP_MAX].value < min_value)
goto out;
+ /* Find a valid group_id */
+ ret = uclamp_group_find(UCLAMP_MIN, min_value);
+ if (ret == -ENOSPC) {
+ pr_err("Cannot allocate more than %d UTIL_MIN clamp groups\n",
+ CONFIG_UCLAMP_GROUPS_COUNT);
+ goto out;
+ }
+ group_id = ret;
+ ret = 0;
+
/* Update effective clamps to track the most restrictive value */
- cpu_util_update_hier(css, UCLAMP_MIN, min_value);
+ cpu_util_update_hier(css, UCLAMP_MIN, min_value, group_id);
+
+ /* Update TG's reference count */
+ uc_se = &tg->uclamp[UCLAMP_MIN];
+ uclamp_group_get(NULL, UCLAMP_MIN, group_id, uc_se, min_value);
out:
rcu_read_unlock();
@@ -7274,8 +7362,10 @@ static int cpu_util_min_write_u64(struct cgroup_subsys_state *css,
static int cpu_util_max_write_u64(struct cgroup_subsys_state *css,
struct cftype *cftype, u64 max_value)
{
+ struct uclamp_se *uc_se;
struct task_group *tg;
int ret = -EINVAL;
+ int group_id;
if (max_value > SCHED_CAPACITY_SCALE)
return -ERANGE;
@@ -7291,8 +7381,22 @@ static int cpu_util_max_write_u64(struct cgroup_subsys_state *css,
if (tg->uclamp[UCLAMP_MIN].value > max_value)
goto out;
+ /* Find a valid group_id */
+ ret = uclamp_group_find(UCLAMP_MAX, max_value);
+ if (ret == -ENOSPC) {
+ pr_err("Cannot allocate more than %d UTIL_MAX clamp groups\n",
+ CONFIG_UCLAMP_GROUPS_COUNT);
+ goto out;
+ }
+ group_id = ret;
+ ret = 0;
+
/* Update effective clamps to track the most restrictive value */
- cpu_util_update_hier(css, UCLAMP_MAX, max_value);
+ cpu_util_update_hier(css, UCLAMP_MAX, max_value, group_id);
+
+ /* Update TG's reference count */
+ uc_se = &tg->uclamp[UCLAMP_MAX];
+ uclamp_group_get(NULL, UCLAMP_MAX, group_id, uc_se, max_value);
out:
rcu_read_unlock();
--
2.18.0
next prev parent reply other threads:[~2018-08-06 16:41 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-06 16:39 [PATCH v3 00/14] Add utilization clamping support Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 01/14] sched/core: uclamp: extend sched_setattr to support utilization clamping Patrick Bellasi
2018-08-06 16:50 ` Randy Dunlap
2018-08-09 8:39 ` Patrick Bellasi
2018-08-09 15:20 ` Randy Dunlap
2018-08-07 9:59 ` Juri Lelli
2018-08-13 12:14 ` Patrick Bellasi
2018-08-13 12:27 ` Juri Lelli
2018-08-07 12:35 ` Juri Lelli
2018-08-09 9:14 ` Patrick Bellasi
2018-08-09 9:50 ` Juri Lelli
2018-08-09 15:23 ` Patrick Bellasi
2018-08-10 7:50 ` Juri Lelli
2018-08-17 10:34 ` Quentin Perret
2018-08-17 10:57 ` Patrick Bellasi
2018-08-17 11:14 ` Quentin Perret
2018-08-06 16:39 ` [PATCH v3 02/14] sched/core: uclamp: map TASK's clamp values into CPU's clamp groups Patrick Bellasi
2018-08-14 11:25 ` Pavan Kondeti
2018-08-14 15:21 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 03/14] sched/core: uclamp: add CPU's clamp groups accounting Patrick Bellasi
2018-08-14 15:44 ` Dietmar Eggemann
2018-08-14 16:49 ` Patrick Bellasi
2018-08-15 9:37 ` Dietmar Eggemann
2018-08-15 10:54 ` Patrick Bellasi
2018-08-15 10:59 ` Dietmar Eggemann
2018-08-16 13:32 ` Patrick Bellasi
2018-08-16 13:37 ` Quentin Perret
2018-08-16 13:45 ` Dietmar Eggemann
2018-08-16 14:21 ` Quentin Perret
2018-08-16 15:00 ` Dietmar Eggemann
2018-08-17 11:04 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 04/14] sched/core: uclamp: update CPU's refcount on clamp changes Patrick Bellasi
2018-08-15 15:02 ` Dietmar Eggemann
2018-08-16 13:22 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 05/14] sched/cpufreq: uclamp: add utilization clamping for FAIR tasks Patrick Bellasi
2018-08-08 13:18 ` Vincent Guittot
2018-08-09 15:30 ` Patrick Bellasi
2018-08-15 15:30 ` Dietmar Eggemann
2018-08-16 13:53 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 06/14] sched/cpufreq: uclamp: add utilization clamping for RT tasks Patrick Bellasi
2018-08-07 13:26 ` Juri Lelli
2018-08-09 15:34 ` Patrick Bellasi
2018-08-09 16:03 ` Vincent Guittot
2018-08-13 10:12 ` Patrick Bellasi
2018-08-13 10:50 ` Juri Lelli
2018-08-13 12:07 ` Vincent Guittot
2018-08-13 12:09 ` Vincent Guittot
2018-08-13 12:49 ` Patrick Bellasi
2018-08-13 14:06 ` Vincent Guittot
2018-08-13 15:01 ` Patrick Bellasi
2018-08-16 10:34 ` Dietmar Eggemann
2018-08-16 13:40 ` Patrick Bellasi
2018-08-07 13:54 ` Quentin Perret
2018-08-09 15:41 ` Patrick Bellasi
2018-08-09 15:55 ` Quentin Perret
2018-08-13 10:17 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 07/14] sched/core: uclamp: enforce last task UCLAMP_MAX Patrick Bellasi
2018-08-16 15:43 ` Dietmar Eggemann
2018-08-16 16:47 ` Patrick Bellasi
2018-08-16 17:10 ` Dietmar Eggemann
2018-08-16 17:27 ` Patrick Bellasi
2018-08-16 17:20 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 08/14] sched/core: uclamp: extend cpu's cgroup controller Patrick Bellasi
2018-08-17 12:21 ` Dietmar Eggemann
2018-08-17 14:24 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 09/14] sched/core: uclamp: propagate parent clamps Patrick Bellasi
2018-08-16 9:09 ` Pavan Kondeti
2018-08-16 14:07 ` Patrick Bellasi
2018-08-17 13:43 ` Dietmar Eggemann
2018-08-17 14:45 ` Patrick Bellasi
2018-08-17 15:50 ` Dietmar Eggemann
2018-08-20 10:01 ` Dietmar Eggemann
2018-08-20 12:28 ` Patrick Bellasi
2018-08-06 16:39 ` Patrick Bellasi [this message]
2018-08-06 16:39 ` [PATCH v3 11/14] sched/core: uclamp: use TG's clamps to restrict Task's clamps Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 12/14] sched/core: uclamp: add system default clamps Patrick Bellasi
2018-08-16 9:13 ` Pavan Kondeti
2018-08-16 14:37 ` Patrick Bellasi
2018-08-20 10:18 ` Dietmar Eggemann
2018-08-20 12:27 ` Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 13/14] sched/core: uclamp: update CPU's refcount on TG's clamp changes Patrick Bellasi
2018-08-06 16:39 ` [PATCH v3 14/14] sched/core: uclamp: use percentage clamp values Patrick Bellasi
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