sched: Expose some macros related to priority

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 moves 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>
Cc: raistlin@linux.it
Cc: juri.lelli@gmail.com
Cc: clark.williams@gmail.com
Cc: rostedt@goodmis.org
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/2b022810905b52d13238466807f4b2a691577180.1390859827.git.yangds.fnst@cn.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/include/linux/sched/prio.h b/include/linux/sched/prio.h
index 9382ba84d5d0..13216f16762e 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 */