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| author |   GeunSik Lim <leemgs1@gmail.com> | 2009-05-28 10:36:11 +0900 |
|---|---|---|
| committer |   Ingo Molnar <mingo@elte.hu> | 2009-05-29 16:21:08 +0200 |
| commit | 294ae4011530d008c59c4fb9847738e39228821e (patch) | |
| tree | f34f000e0bc1066140bbbc090fa624cb96cfb44c /Documentation | |
| parent | sched: properly define the sched_group::cpumask and sched_domain::span fields (diff) | |
| download | linux-dev-294ae4011530d008c59c4fb9847738e39228821e.tar.xz linux-dev-294ae4011530d008c59c4fb9847738e39228821e.zip | |
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@samsung.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | 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 fd9a3e693813..e362f50c496f 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: |