[PATCH v3 1/2] sched/deadline: don't need to check throttled status when switched to dl

[PATCH v3 1/2] sched/deadline: don't need to check throttled status when switched to dl

[Wanpeng Li]

After commit 40767b0dc768 ("sched/deadline: Fix deadline parameter
modification handling") is merged, deadline task throttled status 
is cleared each time once switch from dl class, so throttled status 
always doesn't set when switch back, there is no need to check 
throttled status, this patch drop the check.

Acked-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
---
v2 -> v3:
 * update changelog

 kernel/sched/deadline.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 27b9381..eed6529 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1722,14 +1722,6 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)
 {
 	int check_resched = 1;
 
-	/*
-	 * If p is throttled, don't consider the possibility
-	 * of preempting rq->curr, the check will be done right
-	 * after its runtime will get replenished.
-	 */
-	if (unlikely(p->dl.dl_throttled))
-		return;
-
 	if (task_on_rq_queued(p) && rq->curr != p) {
 #ifdef CONFIG_SMP
 		if (p->nr_cpus_allowed > 1 && rq->dl.overloaded &&
-- 
1.9.1

[PATCH v3 2/2] sched/deadline: fix rt runtime corrupt when dl refuse a smaller bandwidth

[Wanpeng Li]

Dl class will refuse the bandwidth to be set to some value smaller
than the current allocated bandwidth in any of the root_domains
through sched_rt_runtime_us and sched_rt_period_us. RT runtime will
be set according to sched_rt_runtime_us before dl class verify if
the new bandwidth is suitable in the case of !CONFIG_RT_GROUP_SCHED.

However, rt runtime will be corrupted if dl refuse the new bandwidth
since there is no undo to reset the rt runtime to the old value.

This patch fix it by verifying new bandwidth for deadline in advance.

Acked-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
---
v2 -> v3:
 * update changelog

 kernel/sched/core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 97fe79c..e884909 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7815,7 +7815,7 @@ static int sched_rt_global_constraints(void)
 }
 #endif /* CONFIG_RT_GROUP_SCHED */
 
-static int sched_dl_global_constraints(void)
+static int sched_dl_global_validate(void)
 {
 	u64 runtime = global_rt_runtime();
 	u64 period = global_rt_period();
@@ -7916,11 +7916,11 @@ int sched_rt_handler(struct ctl_table *table, int write,
 		if (ret)
 			goto undo;
 
-		ret = sched_rt_global_constraints();
+		ret = sched_dl_global_validate();
 		if (ret)
 			goto undo;
 
-		ret = sched_dl_global_constraints();
+		ret = sched_rt_global_constraints();
 		if (ret)
 			goto undo;
 
-- 
1.9.1

Re: [PATCH v3 1/2] sched/deadline: don't need to check throttled status when switched to dl

[Wanpeng Li]

Hi Ingo, how about these three patches this time, sorry for my bad english.
On Tue, Mar 17, 2015 at 07:15:30PM +0800, Wanpeng Li wrote:
>After commit 40767b0dc768 ("sched/deadline: Fix deadline parameter
>modification handling") is merged, deadline task throttled status 
>is cleared each time once switch from dl class, so throttled status 
>always doesn't set when switch back, there is no need to check 
>throttled status, this patch drop the check.
>
>Acked-by: Juri Lelli <juri.lelli@arm.com>
>Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
>---
>v2 -> v3:
> * update changelog
>
> kernel/sched/deadline.c | 8 --------
> 1 file changed, 8 deletions(-)
>
>diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
>index 27b9381..eed6529 100644
>--- a/kernel/sched/deadline.c
>+++ b/kernel/sched/deadline.c
>@@ -1722,14 +1722,6 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)
> {
> 	int check_resched = 1;
> 
>-	/*
>-	 * If p is throttled, don't consider the possibility
>-	 * of preempting rq->curr, the check will be done right
>-	 * after its runtime will get replenished.
>-	 */
>-	if (unlikely(p->dl.dl_throttled))
>-		return;
>-
> 	if (task_on_rq_queued(p) && rq->curr != p) {
> #ifdef CONFIG_SMP
> 		if (p->nr_cpus_allowed > 1 && rq->dl.overloaded &&
>-- 
>1.9.1

[tip:sched/core] sched/deadline: Avoid a superfluous check

[tip-bot for Wanpeng Li]

Commit-ID:  bd4bde14b93cce8fa77765ff709e0be55abdba2c
Gitweb:     http://git.kernel.org/tip/bd4bde14b93cce8fa77765ff709e0be55abdba2c
Author:     Wanpeng Li <wanpeng.li@linux.intel.com>
AuthorDate: Tue, 17 Mar 2015 19:15:30 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 27 Mar 2015 09:36:12 +0100

sched/deadline: Avoid a superfluous check

Since commit 40767b0dc768 ("sched/deadline: Fix deadline parameter
modification handling") we clear the thottled state when switching
from a dl task, therefore we should never find it set in switching to
a dl task.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
[ Improved the changelog. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@arm.com>
Link: http://lkml.kernel.org/r/1426590931-4639-1-git-send-email-wanpeng.li@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/deadline.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 0a81a95..24c18dc 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1665,14 +1665,6 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)
 {
 	int check_resched = 1;
 
-	/*
-	 * If p is throttled, don't consider the possibility
-	 * of preempting rq->curr, the check will be done right
-	 * after its runtime will get replenished.
-	 */
-	if (unlikely(p->dl.dl_throttled))
-		return;
-
 	if (task_on_rq_queued(p) && rq->curr != p) {
 #ifdef CONFIG_SMP
 		if (p->nr_cpus_allowed > 1 && rq->dl.overloaded &&

[tip:sched/core] sched/deadline: Fix rt runtime corruption when dl fails its global constraints

[tip-bot for Wanpeng Li]

Commit-ID:  a1963b81deec54c113e770b0020e5f1c3188a087
Gitweb:     http://git.kernel.org/tip/a1963b81deec54c113e770b0020e5f1c3188a087
Author:     Wanpeng Li <wanpeng.li@linux.intel.com>
AuthorDate: Tue, 17 Mar 2015 19:15:31 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 27 Mar 2015 09:36:15 +0100

sched/deadline: Fix rt runtime corruption when dl fails its global constraints

One version of sched_rt_global_constaints() (the !rt-cgroup one)
changes state, therefore if we fail the later sched_dl_global_constraints()
call the state is left in an inconsistent state.

Fix this by changing the order of the calls.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
[ Improved the changelog. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@arm.com>
Link: http://lkml.kernel.org/r/1426590931-4639-2-git-send-email-wanpeng.li@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 043e2a1..4b3b688 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7804,7 +7804,7 @@ static int sched_rt_global_constraints(void)
 }
 #endif /* CONFIG_RT_GROUP_SCHED */
 
-static int sched_dl_global_constraints(void)
+static int sched_dl_global_validate(void)
 {
 	u64 runtime = global_rt_runtime();
 	u64 period = global_rt_period();
@@ -7905,11 +7905,11 @@ int sched_rt_handler(struct ctl_table *table, int write,
 		if (ret)
 			goto undo;
 
-		ret = sched_rt_global_constraints();
+		ret = sched_dl_global_validate();
 		if (ret)
 			goto undo;
 
-		ret = sched_dl_global_constraints();
+		ret = sched_rt_global_constraints();
 		if (ret)
 			goto undo;