Peter,
this patchset replace the beginning of the previous mixed one which was not yet commited [1] without changes except a compilation error fix for UP kernel config. It is refreshed against tip/sched/core.
As the UP config compilation is broken on the previous patchset, git bisect is no longer safe for it. You can apply this small serie and drop the 3 first patches of the previous series [1], or ignore it and I will bring the fix after you applied [1].
It cleanups the idle_balance function parameters by passing the struct rq only, fixes a race in the idle_balance function and finally move the idle_stamp from fair.c to core.c. I am aware it will return back to fair.c with Peter's pending patches but at least it changes the idle_balance() function to return true if a balance occured.
[1] https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg577271.html
Changelog: V2: * fixed compilation errors when CONFIG_SMP=n
V1: initial post
Daniel Lezcano (3): sched: Remove cpu parameter for idle_balance() sched: Fix race in idle_balance() sched: Move idle_stamp up to the core
kernel/sched/core.c | 13 +++++++++++-- kernel/sched/fair.c | 20 +++++++++++++------- kernel/sched/sched.h | 8 +------- 3 files changed, 25 insertions(+), 16 deletions(-)
The cpu parameter passed to idle_balance is not needed as it could be retrieved from the struct rq.
Cc: alex.shi@linaro.org Cc: peterz@infradead.org Cc: mingo@kernel.org Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Signed-off-by: Peter Zijlstra peterz@infradead.org --- kernel/sched/core.c | 2 +- kernel/sched/fair.c | 3 ++- kernel/sched/sched.h | 4 ++-- 3 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 210a12a..16b97dd 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2705,7 +2705,7 @@ need_resched: pre_schedule(rq, prev);
if (unlikely(!rq->nr_running)) - idle_balance(cpu, rq); + idle_balance(rq);
put_prev_task(rq, prev); next = pick_next_task(rq); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 4caa803..428bc9d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6531,12 +6531,13 @@ out: * idle_balance is called by schedule() if this_cpu is about to become * idle. Attempts to pull tasks from other CPUs. */ -void idle_balance(int this_cpu, struct rq *this_rq) +void idle_balance(struct rq *this_rq) { struct sched_domain *sd; int pulled_task = 0; unsigned long next_balance = jiffies + HZ; u64 curr_cost = 0; + int this_cpu = this_rq->cpu;
this_rq->idle_stamp = rq_clock(this_rq);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index c2119fd..1436219 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1176,14 +1176,14 @@ extern const struct sched_class idle_sched_class; extern void update_group_power(struct sched_domain *sd, int cpu);
extern void trigger_load_balance(struct rq *rq); -extern void idle_balance(int this_cpu, struct rq *this_rq); +extern void idle_balance(struct rq *this_rq);
extern void idle_enter_fair(struct rq *this_rq); extern void idle_exit_fair(struct rq *this_rq);
#else /* CONFIG_SMP */
-static inline void idle_balance(int cpu, struct rq *rq) +static inline void idle_balance(struct rq *rq) { }
On 02/07/2014 07:10 AM, Daniel Lezcano wrote:
The cpu parameter passed to idle_balance is not needed as it could be retrieved from the struct rq.
Cc: alex.shi@linaro.org Cc: peterz@infradead.org Cc: mingo@kernel.org Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Signed-off-by: Peter Zijlstra peterz@infradead.org
Reviewed-by: Alex Shi alex.shi@linaro.org
kernel/sched/core.c | 2 +- kernel/sched/fair.c | 3 ++- kernel/sched/sched.h | 4 ++-- 3 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 210a12a..16b97dd 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2705,7 +2705,7 @@ need_resched: pre_schedule(rq, prev); if (unlikely(!rq->nr_running))
idle_balance(cpu, rq);
idle_balance(rq);put_prev_task(rq, prev); next = pick_next_task(rq); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 4caa803..428bc9d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6531,12 +6531,13 @@ out:
- idle_balance is called by schedule() if this_cpu is about to become
- idle. Attempts to pull tasks from other CPUs.
*/ -void idle_balance(int this_cpu, struct rq *this_rq) +void idle_balance(struct rq *this_rq) { struct sched_domain *sd; int pulled_task = 0; unsigned long next_balance = jiffies + HZ; u64 curr_cost = 0;
- int this_cpu = this_rq->cpu;
this_rq->idle_stamp = rq_clock(this_rq); diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index c2119fd..1436219 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1176,14 +1176,14 @@ extern const struct sched_class idle_sched_class; extern void update_group_power(struct sched_domain *sd, int cpu); extern void trigger_load_balance(struct rq *rq); -extern void idle_balance(int this_cpu, struct rq *this_rq); +extern void idle_balance(struct rq *this_rq); extern void idle_enter_fair(struct rq *this_rq); extern void idle_exit_fair(struct rq *this_rq); #else /* CONFIG_SMP */ -static inline void idle_balance(int cpu, struct rq *rq) +static inline void idle_balance(struct rq *rq) { }
The scheduler main function 'schedule()' checks if there are no more tasks on the runqueue. Then it checks if a task should be pulled in the current runqueue in idle_balance() assuming it will go to idle otherwise.
But the idle_balance() releases the rq->lock in order to lookup in the sched domains and takes the lock again right after. That opens a window where another cpu may put a task in our runqueue, so we won't go to idle but we have filled the idle_stamp, thinking we will.
This patch closes the window by checking if the runqueue has been modified but without pulling a task after taking the lock again, so we won't go to idle right after in the __schedule() function.
Cc: alex.shi@linaro.org Cc: peterz@infradead.org Cc: mingo@kernel.org Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Signed-off-by: Peter Zijlstra peterz@infradead.org --- kernel/sched/fair.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 428bc9d..5ebc681 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6589,6 +6589,13 @@ void idle_balance(struct rq *this_rq)
raw_spin_lock(&this_rq->lock);
+ /* + * While browsing the domains, we released the rq lock. + * A task could have be enqueued in the meantime + */ + if (this_rq->nr_running && !pulled_task) + return; + if (pulled_task || time_after(jiffies, this_rq->next_balance)) { /* * We are going idle. next_balance may be set based on
HI Daniel,
Isn't the only scenario where another cpu can put an idle task on our runqueue, in nohz_idle_balance() where only the cpus in the nohz.idle_cpus_mask are iterated through. But for the case that this patch is addressing, the cpu in question is not yet a part of the nohz.idle_cpus_mask right?
Any other case would trigger load balancing on the same cpu, but we are preempt_disabled and interrupt disabled at this point.
Thanks
Regards Preeti U Murthy
On Fri, Feb 7, 2014 at 4:40 AM, Daniel Lezcano daniel.lezcano@linaro.org wrote:
The scheduler main function 'schedule()' checks if there are no more tasks on the runqueue. Then it checks if a task should be pulled in the current runqueue in idle_balance() assuming it will go to idle otherwise.
But the idle_balance() releases the rq->lock in order to lookup in the sched domains and takes the lock again right after. That opens a window where another cpu may put a task in our runqueue, so we won't go to idle but we have filled the idle_stamp, thinking we will.
This patch closes the window by checking if the runqueue has been modified but without pulling a task after taking the lock again, so we won't go to idle right after in the __schedule() function.
Cc: alex.shi@linaro.org Cc: peterz@infradead.org Cc: mingo@kernel.org Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Signed-off-by: Peter Zijlstra peterz@infradead.org
kernel/sched/fair.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 428bc9d..5ebc681 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6589,6 +6589,13 @@ void idle_balance(struct rq *this_rq)
raw_spin_lock(&this_rq->lock);
/** While browsing the domains, we released the rq lock.* A task could have be enqueued in the meantime*/if (this_rq->nr_running && !pulled_task)return;if (pulled_task || time_after(jiffies, this_rq->next_balance)) { /* * We are going idle. next_balance may be set based on-- 1.7.9.5
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On 02/10/2014 10:24 AM, Preeti Murthy wrote:
HI Daniel,
Isn't the only scenario where another cpu can put an idle task on our runqueue,
Well, I am not sure to understand what you meant, but I assume you are asking if it is possible to have a task to be pulled when we are idle, right ?
This patch fixes the race when the current cpu is *about* to enter idle when calling schedule().
in nohz_idle_balance() where only the cpus in the nohz.idle_cpus_mask are iterated through. But for the case that this patch is addressing, the cpu in question is not yet a part of the nohz.idle_cpus_mask right?
Any other case would trigger load balancing on the same cpu, but we are preempt_disabled and interrupt disabled at this point.
Thanks
Regards Preeti U Murthy
On Fri, Feb 7, 2014 at 4:40 AM, Daniel Lezcano daniel.lezcano@linaro.org wrote:
The scheduler main function 'schedule()' checks if there are no more tasks on the runqueue. Then it checks if a task should be pulled in the current runqueue in idle_balance() assuming it will go to idle otherwise.
But the idle_balance() releases the rq->lock in order to lookup in the sched domains and takes the lock again right after. That opens a window where another cpu may put a task in our runqueue, so we won't go to idle but we have filled the idle_stamp, thinking we will.
This patch closes the window by checking if the runqueue has been modified but without pulling a task after taking the lock again, so we won't go to idle right after in the __schedule() function.
Cc: alex.shi@linaro.org Cc: peterz@infradead.org Cc: mingo@kernel.org Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Signed-off-by: Peter Zijlstra peterz@infradead.org
kernel/sched/fair.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 428bc9d..5ebc681 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6589,6 +6589,13 @@ void idle_balance(struct rq *this_rq)
raw_spin_lock(&this_rq->lock);
/** While browsing the domains, we released the rq lock.* A task could have be enqueued in the meantime*/if (this_rq->nr_running && !pulled_task)return;if (pulled_task || time_after(jiffies, this_rq->next_balance)) { /* * We are going idle. next_balance may be set based on-- 1.7.9.5
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On 02/11/2014 07:11 PM, Daniel Lezcano wrote:
On 02/10/2014 10:24 AM, Preeti Murthy wrote:
HI Daniel,
Isn't the only scenario where another cpu can put an idle task on our runqueue,
Well, I am not sure to understand what you meant, but I assume you are asking if it is possible to have a task to be pulled when we are idle, right ?
This patch fixes the race when the current cpu is *about* to enter idle when calling schedule().
Preeti said the she didn't see a possible to insert a task on the cpu.
I also did a quick check, maybe task come from wakeup path?
Hi,
On 02/13/2014 01:15 PM, Alex Shi wrote:
On 02/11/2014 07:11 PM, Daniel Lezcano wrote:
On 02/10/2014 10:24 AM, Preeti Murthy wrote:
HI Daniel,
Isn't the only scenario where another cpu can put an idle task on our runqueue,
Well, I am not sure to understand what you meant, but I assume you are asking if it is possible to have a task to be pulled when we are idle, right ?
This patch fixes the race when the current cpu is *about* to enter idle when calling schedule().
Preeti said the she didn't see a possible to insert a task on the cpu.
I also did a quick check, maybe task come from wakeup path?
Yes this is possible. Thanks for pointing this :)
Reviewed-by: Preeti U Murthy preeti@linux.vnet.ibm.com
On 02/13/2014 11:10 AM, Preeti U Murthy wrote:
Hi,
On 02/13/2014 01:15 PM, Alex Shi wrote:
On 02/11/2014 07:11 PM, Daniel Lezcano wrote:
On 02/10/2014 10:24 AM, Preeti Murthy wrote:
HI Daniel,
Isn't the only scenario where another cpu can put an idle task on our runqueue,
Well, I am not sure to understand what you meant, but I assume you are asking if it is possible to have a task to be pulled when we are idle, right ?
This patch fixes the race when the current cpu is *about* to enter idle when calling schedule().
Preeti said the she didn't see a possible to insert a task on the cpu.
I also did a quick check, maybe task come from wakeup path?
Yes this is possible. Thanks for pointing this :)
Reviewed-by: Preeti U Murthy preeti@linux.vnet.ibm.com
Thanks for the review !
-- Daniel
On 02/07/2014 07:10 AM, Daniel Lezcano wrote:
The scheduler main function 'schedule()' checks if there are no more tasks on the runqueue. Then it checks if a task should be pulled in the current runqueue in idle_balance() assuming it will go to idle otherwise.
But the idle_balance() releases the rq->lock in order to lookup in the sched domains and takes the lock again right after. That opens a window where another cpu may put a task in our runqueue, so we won't go to idle but we have filled the idle_stamp, thinking we will.
This patch closes the window by checking if the runqueue has been modified but without pulling a task after taking the lock again, so we won't go to idle right after in the __schedule() function.
Cc: alex.shi@linaro.org Cc: peterz@infradead.org Cc: mingo@kernel.org Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Signed-off-by: Peter Zijlstra peterz@infradead.org
kernel/sched/fair.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 428bc9d..5ebc681 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6589,6 +6589,13 @@ void idle_balance(struct rq *this_rq) raw_spin_lock(&this_rq->lock);
- /*
* While browsing the domains, we released the rq lock.* A task could have be enqueued in the meantime*/
Mind to move the following line up to here?
if (curr_cost > this_rq->max_idle_balance_cost) this_rq->max_idle_balance_cost = curr_cost;
- if (this_rq->nr_running && !pulled_task)
return;- if (pulled_task || time_after(jiffies, this_rq->next_balance)) { /*
- We are going idle. next_balance may be set based on
The idle_balance modifies the idle_stamp field of the rq, making this information to be shared across core.c and fair.c. As we can know if the cpu is going to idle or not with the previous patch, let's encapsulate the idle_stamp information in core.c by moving it up to the caller. The idle_balance function returns true in case a balancing occured and the cpu won't be idle, false if no balance happened and the cpu is going idle.
Cc: mingo@kernel.org Cc: alex.shi@linaro.org Cc: peterz@infradead.org Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Signed-off-by: Peter Zijlstra peterz@infradead.org --- kernel/sched/core.c | 13 +++++++++++-- kernel/sched/fair.c | 14 ++++++-------- kernel/sched/sched.h | 8 +------- 3 files changed, 18 insertions(+), 17 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 16b97dd..428ee4c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2704,8 +2704,17 @@ need_resched:
pre_schedule(rq, prev);
- if (unlikely(!rq->nr_running)) - idle_balance(rq); +#ifdef CONFIG_SMP + if (unlikely(!rq->nr_running)) { + /* + * We must set idle_stamp _before_ calling idle_balance(), such + * that we measure the duration of idle_balance() as idle time. + */ + rq->idle_stamp = rq_clock(rq); + if (idle_balance(rq)) + rq->idle_stamp = 0; + } +#endif
put_prev_task(rq, prev); next = pick_next_task(rq); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 5ebc681..04fea77 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6531,7 +6531,7 @@ out: * idle_balance is called by schedule() if this_cpu is about to become * idle. Attempts to pull tasks from other CPUs. */ -void idle_balance(struct rq *this_rq) +int idle_balance(struct rq *this_rq) { struct sched_domain *sd; int pulled_task = 0; @@ -6539,10 +6539,8 @@ void idle_balance(struct rq *this_rq) u64 curr_cost = 0; int this_cpu = this_rq->cpu;
- this_rq->idle_stamp = rq_clock(this_rq); - if (this_rq->avg_idle < sysctl_sched_migration_cost) - return; + return 0;
/* * Drop the rq->lock, but keep IRQ/preempt disabled. @@ -6580,10 +6578,8 @@ void idle_balance(struct rq *this_rq) interval = msecs_to_jiffies(sd->balance_interval); if (time_after(next_balance, sd->last_balance + interval)) next_balance = sd->last_balance + interval; - if (pulled_task) { - this_rq->idle_stamp = 0; + if (pulled_task) break; - } } rcu_read_unlock();
@@ -6594,7 +6590,7 @@ void idle_balance(struct rq *this_rq) * A task could have be enqueued in the meantime */ if (this_rq->nr_running && !pulled_task) - return; + return 1;
if (pulled_task || time_after(jiffies, this_rq->next_balance)) { /* @@ -6606,6 +6602,8 @@ void idle_balance(struct rq *this_rq)
if (curr_cost > this_rq->max_idle_balance_cost) this_rq->max_idle_balance_cost = curr_cost; + + return pulled_task; }
/* diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 1436219..c08c070 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1176,17 +1176,11 @@ extern const struct sched_class idle_sched_class; extern void update_group_power(struct sched_domain *sd, int cpu);
extern void trigger_load_balance(struct rq *rq); -extern void idle_balance(struct rq *this_rq); +extern int idle_balance(struct rq *this_rq);
extern void idle_enter_fair(struct rq *this_rq); extern void idle_exit_fair(struct rq *this_rq);
-#else /* CONFIG_SMP */ - -static inline void idle_balance(struct rq *rq) -{ -} - #endif
extern void sysrq_sched_debug_show(void);
Hi Daniel,
On Fri, Feb 7, 2014 at 4:40 AM, Daniel Lezcano daniel.lezcano@linaro.org wrote:
The idle_balance modifies the idle_stamp field of the rq, making this information to be shared across core.c and fair.c. As we can know if the cpu is going to idle or not with the previous patch, let's encapsulate the idle_stamp information in core.c by moving it up to the caller. The idle_balance function returns true in case a balancing occured and the cpu won't be idle, false if no balance happened and the cpu is going idle.
Cc: mingo@kernel.org Cc: alex.shi@linaro.org Cc: peterz@infradead.org Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Signed-off-by: Peter Zijlstra peterz@infradead.org
kernel/sched/core.c | 13 +++++++++++-- kernel/sched/fair.c | 14 ++++++-------- kernel/sched/sched.h | 8 +------- 3 files changed, 18 insertions(+), 17 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 16b97dd..428ee4c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2704,8 +2704,17 @@ need_resched:
pre_schedule(rq, prev);
if (unlikely(!rq->nr_running))idle_balance(rq);+#ifdef CONFIG_SMP
if (unlikely(!rq->nr_running)) {/** We must set idle_stamp _before_ calling idle_balance(), such* that we measure the duration of idle_balance() as idle time.
Should not this be "such that we *do not* measure the duration of idle_balance() as idle time?"
Thanks
Regards Preeti U Murthy
On 02/10/2014 11:04 AM, Preeti Murthy wrote:
Hi Daniel,
On Fri, Feb 7, 2014 at 4:40 AM, Daniel Lezcano daniel.lezcano@linaro.org wrote:
The idle_balance modifies the idle_stamp field of the rq, making this information to be shared across core.c and fair.c. As we can know if the cpu is going to idle or not with the previous patch, let's encapsulate the idle_stamp information in core.c by moving it up to the caller. The idle_balance function returns true in case a balancing occured and the cpu won't be idle, false if no balance happened and the cpu is going idle.
Cc: mingo@kernel.org Cc: alex.shi@linaro.org Cc: peterz@infradead.org Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Signed-off-by: Peter Zijlstra peterz@infradead.org
kernel/sched/core.c | 13 +++++++++++-- kernel/sched/fair.c | 14 ++++++-------- kernel/sched/sched.h | 8 +------- 3 files changed, 18 insertions(+), 17 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 16b97dd..428ee4c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2704,8 +2704,17 @@ need_resched:
pre_schedule(rq, prev);
if (unlikely(!rq->nr_running))idle_balance(rq);+#ifdef CONFIG_SMP
if (unlikely(!rq->nr_running)) {/** We must set idle_stamp _before_ calling idle_balance(), such* that we measure the duration of idle_balance() as idle time.Should not this be "such that we *do not* measure the duration of idle_balance() as idle time?"
Actually, the initial code was including the idle balance time processing in the idle stamp. When I moved the idle stamp in core.c, idle balance was no longer measured (an unwanted change). That has been fixed and to prevent that to occur again, we added a comment.
Hi Daniel,
On 02/11/2014 05:37 PM, Daniel Lezcano wrote:
On 02/10/2014 11:04 AM, Preeti Murthy wrote:
Hi Daniel,
On Fri, Feb 7, 2014 at 4:40 AM, Daniel Lezcano daniel.lezcano@linaro.org wrote:
The idle_balance modifies the idle_stamp field of the rq, making this information to be shared across core.c and fair.c. As we can know if the cpu is going to idle or not with the previous patch, let's encapsulate the idle_stamp information in core.c by moving it up to the caller. The idle_balance function returns true in case a balancing occured and the cpu won't be idle, false if no balance happened and the cpu is going idle.
Cc: mingo@kernel.org Cc: alex.shi@linaro.org Cc: peterz@infradead.org Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Signed-off-by: Peter Zijlstra peterz@infradead.org
kernel/sched/core.c | 13 +++++++++++-- kernel/sched/fair.c | 14 ++++++-------- kernel/sched/sched.h | 8 +------- 3 files changed, 18 insertions(+), 17 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 16b97dd..428ee4c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2704,8 +2704,17 @@ need_resched:
pre_schedule(rq, prev);
if (unlikely(!rq->nr_running))idle_balance(rq);+#ifdef CONFIG_SMP
if (unlikely(!rq->nr_running)) {/** We must set idle_stamp _before_ callingidle_balance(), such
* that we measure the duration of idle_balance() asidle time.
Should not this be "such that we *do not* measure the duration of idle_balance() as idle time?"
Actually, the initial code was including the idle balance time processing in the idle stamp. When I moved the idle stamp in core.c, idle balance was no longer measured (an unwanted change). That has been fixed and to prevent that to occur again, we added a comment.
Oh sorry! Yes you are right.
Thanks
Regards Preeti U Murthy
On 02/07/2014 07:10 AM, Daniel Lezcano wrote:
The idle_balance modifies the idle_stamp field of the rq, making this information to be shared across core.c and fair.c. As we can know if the cpu is going to idle or not with the previous patch, let's encapsulate the idle_stamp information in core.c by moving it up to the caller. The idle_balance function returns true in case a balancing occured and the cpu won't be idle, false if no balance happened and the cpu is going idle.
Cc: mingo@kernel.org Cc: alex.shi@linaro.org Cc: peterz@infradead.org Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Signed-off-by: Peter Zijlstra peterz@infradead.org
Reviewed-by: Alex Shi alex.shi@linaro.org
linaro-kernel@lists.linaro.org
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Alex Shi -
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