Commit-ID: 294ae4011530d008c59c4fb9847738e39228821e
Gitweb: http://git.kernel.org/tip/294ae4011530d008c59c4fb9847738e39228821e
Author: GeunSik Lim <leemgs1@xxxxxxxxx>
AuthorDate: Thu, 28 May 2009 10:36:11 +0900
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Fri, 29 May 2009 16:21:08 +0200
ftrace: fix typo about map of kernel priority in ftrace.txt file.
Fix typo about chart to map the kernel priority to user land priorities.
* About sched_setscheduler(2)
Processes scheduled under SCHED_FIFO or SCHED_RR
can have a (user-space) static priority in the range 1 to 99.
(reference: http://www.kernel.org/doc/man-pages/online/pages/
man2/sched_setscheduler.2.html)
* From: Steven Rostedt
0 to 98 - maps to RT tasks 99 to 1 (SCHED_RR or SCHED_FIFO)
99 - maps to internal kernel threads that want to be lower than RT tasks
but higher than SCHED_OTHER tasks. Although I'm not sure if any
kernel thread actually uses this. I'm not even sure how this can be
set, because the internal sched_setscheduler function does not allow
for it.
100 to 139 - maps nice levels -20 to 19. These are not set via
sched_setscheduler, but are set via the nice system call.
140 - reserved for idle tasks.
Signed-off-by: GeunSik Lim <geunsik.lim@xxxxxxxxxxx>
Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
Documentation/trace/ftrace.txt | 15 ++++++++++++---
1 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index fd9a3e6..e362f50 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -518,9 +518,18 @@ priority with zero (0) being the highest priority and the nice
values starting at 100 (nice -20). Below is a quick chart to map
the kernel priority to user land priorities.
- Kernel priority: 0 to 99 ==> user RT priority 99 to 0
- Kernel priority: 100 to 139 ==> user nice -20 to 19
- Kernel priority: 140 ==> idle task priority
+ Kernel Space User Space
+ ===============================================================
+ 0(high) to 98(low) user RT priority 99(high) to 1(low)
+ with SCHED_RR or SCHED_FIFO
+ ---------------------------------------------------------------
+ 99 sched_priority is not used in scheduling
+ decisions(it must be specified as 0)
+ ---------------------------------------------------------------
+ 100(high) to 139(low) user nice -20(high) to 19(low)
+ ---------------------------------------------------------------
+ 140 idle task priority
+ ---------------------------------------------------------------
The task states are:
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