[PATCH 0/3 V2] sched: Collect the bits about priority into a new header file, include/linux/sched/prio.h.

[PATCH 0/3 V2] sched: Collect the bits about priority into a new header file, include/linux/sched/prio.h.

[Dongsheng Yang]

Hi Peter,
    This patchset is version 2 about priority of sched. Please help to review. 

    Sorry for the late update about it, coming back from vacation.

    v2:
    	* leave the task_prio() in kernel/sched/core.c
    	* remove macro TASK_NICE and implement it as static inline
      	  function in include/linux/sched.h.
	* remove #ifndef when include prio.h.

Dongsheng Yang (3):
  sched: Move the priority specific bits into a new header file.
  sched: Expose some macros related with priority.
  sched: Implement task_nice as static inline function.

 include/linux/sched.h      | 12 +++++++++++-
 include/linux/sched/prio.h | 40 ++++++++++++++++++++++++++++++++++++++++
 include/linux/sched/rt.h   | 19 +------------------
 kernel/sched/core.c        | 26 +++++++-------------------
 kernel/sched/cputime.c     |  4 ++--
 kernel/sched/sched.h       | 18 ------------------
 6 files changed, 61 insertions(+), 58 deletions(-)
 create mode 100644 include/linux/sched/prio.h

-- 
1.8.2.1

[PATCH 1/3] sched: Move the priority specific bits into a new header file.

[Dongsheng Yang]

Some bits about priority are defined in linux/sched/rt.h, but
some of them are not only for rt scheduler, such as MAX_PRIO.

This patch move them all into a new header file, linux/sched/prio.h.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
---
 include/linux/sched.h      |  1 +
 include/linux/sched/prio.h | 23 +++++++++++++++++++++++
 include/linux/sched/rt.h   | 19 +------------------
 3 files changed, 25 insertions(+), 18 deletions(-)
 create mode 100644 include/linux/sched/prio.h

diff --git a/include/linux/sched.h b/include/linux/sched.h
index a781dec..5aa0329 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -54,6 +54,7 @@ struct sched_param {
 #include <linux/llist.h>
 #include <linux/uidgid.h>
 #include <linux/gfp.h>
+#include <linux/sched/prio.h>
 
 #include <asm/processor.h>
 
diff --git a/include/linux/sched/prio.h b/include/linux/sched/prio.h
new file mode 100644
index 0000000..9382ba8
--- /dev/null
+++ b/include/linux/sched/prio.h
@@ -0,0 +1,23 @@
+#ifndef _SCHED_PRIO_H
+#define _SCHED_PRIO_H
+
+/*
+ * Priority of a process goes from 0..MAX_PRIO-1, valid RT
+ * priority is 0..MAX_RT_PRIO-1, and SCHED_NORMAL/SCHED_BATCH
+ * tasks are in the range MAX_RT_PRIO..MAX_PRIO-1. Priority
+ * values are inverted: lower p->prio value means higher priority.
+ *
+ * The MAX_USER_RT_PRIO value allows the actual maximum
+ * RT priority to be separate from the value exported to
+ * user-space.  This allows kernel threads to set their
+ * priority to a value higher than any user task. Note:
+ * MAX_RT_PRIO must not be smaller than MAX_USER_RT_PRIO.
+ */
+
+#define MAX_USER_RT_PRIO	100
+#define MAX_RT_PRIO		MAX_USER_RT_PRIO
+
+#define MAX_PRIO		(MAX_RT_PRIO + 40)
+#define DEFAULT_PRIO		(MAX_RT_PRIO + 20)
+
+#endif /* _SCHED_PRIO_H */
diff --git a/include/linux/sched/rt.h b/include/linux/sched/rt.h
index 34e4ebe..f7453d4 100644
--- a/include/linux/sched/rt.h
+++ b/include/linux/sched/rt.h
@@ -1,24 +1,7 @@
 #ifndef _SCHED_RT_H
 #define _SCHED_RT_H
 
-/*
- * Priority of a process goes from 0..MAX_PRIO-1, valid RT
- * priority is 0..MAX_RT_PRIO-1, and SCHED_NORMAL/SCHED_BATCH
- * tasks are in the range MAX_RT_PRIO..MAX_PRIO-1. Priority
- * values are inverted: lower p->prio value means higher priority.
- *
- * The MAX_USER_RT_PRIO value allows the actual maximum
- * RT priority to be separate from the value exported to
- * user-space.  This allows kernel threads to set their
- * priority to a value higher than any user task. Note:
- * MAX_RT_PRIO must not be smaller than MAX_USER_RT_PRIO.
- */
-
-#define MAX_USER_RT_PRIO	100
-#define MAX_RT_PRIO		MAX_USER_RT_PRIO
-
-#define MAX_PRIO		(MAX_RT_PRIO + 40)
-#define DEFAULT_PRIO		(MAX_RT_PRIO + 20)
+#include <linux/sched/prio.h>
 
 static inline int rt_prio(int prio)
 {
-- 
1.8.2.1

[PATCH 2/3] sched: Expose some macros related with priority.

[Dongsheng Yang]

Some macros in kernel/sched/sched.h about priority are
private to kernel/sched. But they are useful to other
parts of the core kernel.

This patch move these macros from kernel/sched/sched.h to
include/linux/sched/prio.h so that they are available to
other subsystems.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
---
 include/linux/sched/prio.h | 18 ++++++++++++++++++
 kernel/sched/sched.h       | 18 ------------------
 2 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/include/linux/sched/prio.h b/include/linux/sched/prio.h
index 9382ba8..13216f1 100644
--- a/include/linux/sched/prio.h
+++ b/include/linux/sched/prio.h
@@ -20,4 +20,22 @@
 #define MAX_PRIO		(MAX_RT_PRIO + 40)
 #define DEFAULT_PRIO		(MAX_RT_PRIO + 20)
 
+/*
+ * Convert user-nice values [ -20 ... 0 ... 19 ]
+ * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
+ * and back.
+ */
+#define NICE_TO_PRIO(nice)	(MAX_RT_PRIO + (nice) + 20)
+#define PRIO_TO_NICE(prio)	((prio) - MAX_RT_PRIO - 20)
+#define TASK_NICE(p)		PRIO_TO_NICE((p)->static_prio)
+
+/*
+ * 'User priority' is the nice value converted to something we
+ * can work with better when scaling various scheduler parameters,
+ * it's a [ 0 ... 39 ] range.
+ */
+#define USER_PRIO(p)		((p)-MAX_RT_PRIO)
+#define TASK_USER_PRIO(p)	USER_PRIO((p)->static_prio)
+#define MAX_USER_PRIO		(USER_PRIO(MAX_PRIO))
+
 #endif /* _SCHED_PRIO_H */
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c2119fd..b44720d 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -24,24 +24,6 @@ extern long calc_load_fold_active(struct rq *this_rq);
 extern void update_cpu_load_active(struct rq *this_rq);
 
 /*
- * Convert user-nice values [ -20 ... 0 ... 19 ]
- * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
- * and back.
- */
-#define NICE_TO_PRIO(nice)	(MAX_RT_PRIO + (nice) + 20)
-#define PRIO_TO_NICE(prio)	((prio) - MAX_RT_PRIO - 20)
-#define TASK_NICE(p)		PRIO_TO_NICE((p)->static_prio)
-
-/*
- * 'User priority' is the nice value converted to something we
- * can work with better when scaling various scheduler parameters,
- * it's a [ 0 ... 39 ] range.
- */
-#define USER_PRIO(p)		((p)-MAX_RT_PRIO)
-#define TASK_USER_PRIO(p)	USER_PRIO((p)->static_prio)
-#define MAX_USER_PRIO		(USER_PRIO(MAX_PRIO))
-
-/*
  * Helpers for converting nanosecond timing to jiffy resolution
  */
 #define NS_TO_JIFFIES(TIME)	((unsigned long)(TIME) / (NSEC_PER_SEC / HZ))
-- 
1.8.2.1

[PATCH 3/3] sched: Implement task_nice as static inline function.

[Dongsheng Yang]

As commit 0e0c0797 expose the priority related macros in linux/sched/prio.h,
we don't have to implement task_nice in kernel/sched/core.c any more.

This patch implement it in linux/sched/sched.h as static inline function,
saving the kernel stack and enhancing the performance.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
---
 include/linux/sched.h      | 11 ++++++++++-
 include/linux/sched/prio.h |  1 -
 kernel/sched/core.c        | 26 +++++++-------------------
 kernel/sched/cputime.c     |  4 ++--
 4 files changed, 19 insertions(+), 23 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5aa0329..65fcbae 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2081,7 +2081,16 @@ static inline void sched_autogroup_exit(struct signal_struct *sig) { }
 extern bool yield_to(struct task_struct *p, bool preempt);
 extern void set_user_nice(struct task_struct *p, long nice);
 extern int task_prio(const struct task_struct *p);
-extern int task_nice(const struct task_struct *p);
+/**
+ * task_nice - return the nice value of a given task.
+ * @p: the task in question.
+ *
+ * Return: The nice value [ -20 ... 0 ... 19 ].
+ */
+static inline int task_nice(const struct task_struct *p)
+{
+	return PRIO_TO_NICE((p)->static_prio);
+}
 extern int can_nice(const struct task_struct *p, const int nice);
 extern int task_curr(const struct task_struct *p);
 extern int idle_cpu(int cpu);
diff --git a/include/linux/sched/prio.h b/include/linux/sched/prio.h
index 13216f1..410ccb7 100644
--- a/include/linux/sched/prio.h
+++ b/include/linux/sched/prio.h
@@ -27,7 +27,6 @@
  */
 #define NICE_TO_PRIO(nice)	(MAX_RT_PRIO + (nice) + 20)
 #define PRIO_TO_NICE(prio)	((prio) - MAX_RT_PRIO - 20)
-#define TASK_NICE(p)		PRIO_TO_NICE((p)->static_prio)
 
 /*
  * 'User priority' is the nice value converted to something we
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b46131e..8d45a47 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2998,7 +2998,7 @@ void set_user_nice(struct task_struct *p, long nice)
 	unsigned long flags;
 	struct rq *rq;
 
-	if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
+	if (task_nice(p) == nice || nice < -20 || nice > 19)
 		return;
 	/*
 	 * We have to be careful, if called from sys_setpriority(),
@@ -3076,7 +3076,7 @@ SYSCALL_DEFINE1(nice, int, increment)
 	if (increment > 40)
 		increment = 40;
 
-	nice = TASK_NICE(current) + increment;
+	nice = task_nice(current) + increment;
 	if (nice < -20)
 		nice = -20;
 	if (nice > 19)
@@ -3109,18 +3109,6 @@ int task_prio(const struct task_struct *p)
 }
 
 /**
- * task_nice - return the nice value of a given task.
- * @p: the task in question.
- *
- * Return: The nice value [ -20 ... 0 ... 19 ].
- */
-int task_nice(const struct task_struct *p)
-{
-	return TASK_NICE(p);
-}
-EXPORT_SYMBOL(task_nice);
-
-/**
  * idle_cpu - is a given cpu idle currently?
  * @cpu: the processor in question.
  *
@@ -3319,7 +3307,7 @@ recheck:
 	 */
 	if (user && !capable(CAP_SYS_NICE)) {
 		if (fair_policy(policy)) {
-			if (attr->sched_nice < TASK_NICE(p) &&
+			if (attr->sched_nice < task_nice(p) &&
 			    !can_nice(p, attr->sched_nice))
 				return -EPERM;
 		}
@@ -3343,7 +3331,7 @@ recheck:
 		 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
 		 */
 		if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) {
-			if (!can_nice(p, TASK_NICE(p)))
+			if (!can_nice(p, task_nice(p)))
 				return -EPERM;
 		}
 
@@ -3383,7 +3371,7 @@ recheck:
 	 * If not changing anything there's no need to proceed further:
 	 */
 	if (unlikely(policy == p->policy)) {
-		if (fair_policy(policy) && attr->sched_nice != TASK_NICE(p))
+		if (fair_policy(policy) && attr->sched_nice != task_nice(p))
 			goto change;
 		if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
 			goto change;
@@ -3835,7 +3823,7 @@ SYSCALL_DEFINE3(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
 	else if (task_has_rt_policy(p))
 		attr.sched_priority = p->rt_priority;
 	else
-		attr.sched_nice = TASK_NICE(p);
+		attr.sched_nice = task_nice(p);
 
 	rcu_read_unlock();
 
@@ -7008,7 +6996,7 @@ void normalize_rt_tasks(void)
 			 * Renice negative nice level userspace
 			 * tasks back to 0:
 			 */
-			if (TASK_NICE(p) < 0 && p->mm)
+			if (task_nice(p) < 0 && p->mm)
 				set_user_nice(p, 0);
 			continue;
 		}
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 9994791..58624a6 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -142,7 +142,7 @@ void account_user_time(struct task_struct *p, cputime_t cputime,
 	p->utimescaled += cputime_scaled;
 	account_group_user_time(p, cputime);
 
-	index = (TASK_NICE(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
+	index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
 
 	/* Add user time to cpustat. */
 	task_group_account_field(p, index, (__force u64) cputime);
@@ -169,7 +169,7 @@ static void account_guest_time(struct task_struct *p, cputime_t cputime,
 	p->gtime += cputime;
 
 	/* Add guest time to cpustat. */
-	if (TASK_NICE(p) > 0) {
+	if (task_nice(p) > 0) {
 		cpustat[CPUTIME_NICE] += (__force u64) cputime;
 		cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime;
 	} else {
-- 
1.8.2.1