From: Alex Shi <alex.shi@intel.com>
To: mingo@redhat.com, peterz@infradead.org, tglx@linutronix.de,
akpm@linux-foundation.org, arjan@linux.intel.com, bp@alien8.de,
pjt@google.com, namhyung@kernel.org, efault@gmx.de,
morten.rasmussen@arm.com
Cc: vincent.guittot@linaro.org, gregkh@linuxfoundation.org,
preeti@linux.vnet.ibm.com, viresh.kumar@linaro.org,
linux-kernel@vger.kernel.org, alex.shi@intel.com,
len.brown@intel.com, rafael.j.wysocki@intel.com, jkosina@suse.cz,
clark.williams@gmail.com, tony.luck@intel.com,
keescook@chromium.org, mgorman@suse.de, riel@redhat.com
Subject: [Resend patch v8 03/13] sched: set initial value of runnable avg for new forked task
Date: Thu, 20 Jun 2013 10:18:47 +0800 [thread overview]
Message-ID: <1371694737-29336-4-git-send-email-alex.shi@intel.com> (raw)
In-Reply-To: <1371694737-29336-1-git-send-email-alex.shi@intel.com>
We need initialize the se.avg.{decay_count, load_avg_contrib} for a
new forked task.
Otherwise random values of above variables cause mess when do new task
enqueue:
enqueue_task_fair
enqueue_entity
enqueue_entity_load_avg
and make forking balancing imbalance since incorrect load_avg_contrib.
Further more, Morten Rasmussen notice some tasks were not launched at
once after created. So Paul and Peter suggest giving a start value for
new task runnable avg time same as sched_slice().
Paul also contribute most of code comments in this commit.
Signed-off-by: Alex Shi <alex.shi@intel.com>
Reviewed-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Reviewed-by: Paul Turner <pjt@google.com>
---
kernel/sched/core.c | 6 ++----
kernel/sched/fair.c | 24 ++++++++++++++++++++++++
kernel/sched/sched.h | 2 ++
3 files changed, 28 insertions(+), 4 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b9e7036..c78a9e2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1598,10 +1598,6 @@ static void __sched_fork(struct task_struct *p)
p->se.vruntime = 0;
INIT_LIST_HEAD(&p->se.group_node);
-#ifdef CONFIG_SMP
- p->se.avg.runnable_avg_period = 0;
- p->se.avg.runnable_avg_sum = 0;
-#endif
#ifdef CONFIG_SCHEDSTATS
memset(&p->se.statistics, 0, sizeof(p->se.statistics));
#endif
@@ -1745,6 +1741,8 @@ void wake_up_new_task(struct task_struct *p)
set_task_cpu(p, select_task_rq(p, SD_BALANCE_FORK, 0));
#endif
+ /* Initialize new task's runnable average */
+ init_task_runnable_average(p);
rq = __task_rq_lock(p);
activate_task(rq, p, 0);
p->on_rq = 1;
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f404468..df5b8a9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -680,6 +680,26 @@ static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
return calc_delta_fair(sched_slice(cfs_rq, se), se);
}
+#ifdef CONFIG_SMP
+static inline void __update_task_entity_contrib(struct sched_entity *se);
+
+/* Give new task start runnable values to heavy its load in infant time */
+void init_task_runnable_average(struct task_struct *p)
+{
+ u32 slice;
+
+ p->se.avg.decay_count = 0;
+ slice = sched_slice(task_cfs_rq(p), &p->se) >> 10;
+ p->se.avg.runnable_avg_sum = slice;
+ p->se.avg.runnable_avg_period = slice;
+ __update_task_entity_contrib(&p->se);
+}
+#else
+void init_task_runnable_average(struct task_struct *p)
+{
+}
+#endif
+
/*
* Update the current task's runtime statistics. Skip current tasks that
* are not in our scheduling class.
@@ -1527,6 +1547,10 @@ static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
* We track migrations using entity decay_count <= 0, on a wake-up
* migration we use a negative decay count to track the remote decays
* accumulated while sleeping.
+ *
+ * Newly forked tasks are enqueued with se->avg.decay_count == 0, they
+ * are seen by enqueue_entity_load_avg() as a migration with an already
+ * constructed load_avg_contrib.
*/
if (unlikely(se->avg.decay_count <= 0)) {
se->avg.last_runnable_update = rq_clock_task(rq_of(cfs_rq));
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 24b1503..0684c26 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1058,6 +1058,8 @@ extern void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime
extern void update_idle_cpu_load(struct rq *this_rq);
+extern void init_task_runnable_average(struct task_struct *p);
+
#ifdef CONFIG_PARAVIRT
static inline u64 steal_ticks(u64 steal)
{
--
1.7.12
next prev parent reply other threads:[~2013-06-20 2:20 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-20 2:18 [Resend patch v8 0/13] use runnable load in schedule balance Alex Shi
2013-06-20 2:18 ` [Resend patch v8 01/13] Revert "sched: Introduce temporary FAIR_GROUP_SCHED dependency for load-tracking" Alex Shi
2013-06-26 5:05 ` Alex Shi
2013-06-26 20:30 ` Ingo Molnar
2013-06-27 1:07 ` Alex Shi
2013-06-27 9:01 ` [tip:sched/core] " tip-bot for Alex Shi
2013-06-20 2:18 ` [Resend patch v8 02/13] sched: move few runnable tg variables into CONFIG_SMP Alex Shi
2013-06-27 9:01 ` [tip:sched/core] sched: Move a " tip-bot for Alex Shi
2013-06-20 2:18 ` Alex Shi [this message]
2013-06-27 9:01 ` [tip:sched/core] sched: Set an initial value of runnable avg for new forked task tip-bot for Alex Shi
2013-06-20 2:18 ` [Resend patch v8 04/13] sched: fix slept time double counting in enqueue entity Alex Shi
2013-06-27 9:01 ` [tip:sched/core] sched: Fix sleep time double accounting " tip-bot for Alex Shi
2013-06-20 2:18 ` [Resend patch v8 05/13] sched: update cpu load after task_tick Alex Shi
2013-06-27 9:02 ` [tip:sched/core] sched: Update " tip-bot for Alex Shi
2013-06-20 2:18 ` [Resend patch v8 06/13] sched: compute runnable load avg in cpu_load and cpu_avg_load_per_task Alex Shi
2013-06-20 13:29 ` Vincent Guittot
2013-06-24 9:06 ` Alex Shi
2013-06-24 10:54 ` Paul Turner
2013-06-24 11:04 ` Vincent Guittot
2013-06-24 11:06 ` Paul Turner
2013-06-24 14:56 ` Alex Shi
2013-06-27 9:02 ` [tip:sched/core] sched: Compute " tip-bot for Alex Shi
2013-06-27 13:30 ` [Resend patch v8 06/13] sched: compute " Alex Shi
2013-06-20 2:18 ` [Resend patch v8 07/13] sched: consider runnable load average in move_tasks Alex Shi
2013-06-27 9:02 ` [tip:sched/core] sched: Consider runnable load average in move_tasks() tip-bot for Alex Shi
2013-06-20 2:18 ` [Resend patch v8 08/13] sched/tg: remove blocked_load_avg in balance Alex Shi
2013-06-20 2:18 ` [Resend patch v8 09/13] sched: change cfs_rq load avg to unsigned long Alex Shi
2013-06-27 9:02 ` [tip:sched/core] sched: Change " tip-bot for Alex Shi
2013-06-20 2:18 ` [Resend patch v8 10/13] sched/tg: use 'unsigned long' for load variable in task group Alex Shi
2013-06-27 9:02 ` [tip:sched/core] sched/tg: Use " tip-bot for Alex Shi
2013-06-20 2:18 ` [Resend patch v8 11/13] sched/cfs_rq: change atomic64_t removed_load to atomic_long_t Alex Shi
2013-06-27 9:02 ` [tip:sched/core] sched/cfs_rq: Change " tip-bot for Alex Shi
2013-06-20 2:18 ` [Resend patch v8 12/13] sched/tg: remove tg.load_weight Alex Shi
2013-06-27 9:02 ` [tip:sched/core] sched/tg: Remove tg.load_weight tip-bot for Alex Shi
2013-06-20 2:18 ` [Resend patch v8 13/13] sched: get_rq_runnable_load() can be static and inline Alex Shi
2013-06-27 9:03 ` [tip:sched/core] sched: Change get_rq_runnable_load() to " tip-bot for Alex Shi
2013-06-24 3:15 ` [Resend patch v8 0/13] use runnable load in schedule balance Alex Shi
2013-06-24 10:40 ` Paul Turner
2013-06-24 15:37 ` Alex Shi
2013-06-25 13:13 ` Alex Shi
2013-06-28 10:56 ` Paul Turner
2013-06-28 11:07 ` Peter Zijlstra
2013-06-28 11:12 ` Alex Shi
2013-10-28 10:25 ` Frederic Weisbecker
2013-10-28 12:22 ` Peter Zijlstra
[not found] ` <CAGjg+kGUo8vqv6hzobuyNoQjipLBXXofZ5q1rUyEehbD3cba9A@mail.gmail.com>
2013-06-28 16:00 ` Paul Turner
2013-07-09 8:53 ` Alex Shi
2013-06-26 14:27 ` Peter Zijlstra
2013-06-26 15:23 ` Alex Shi
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