commit 16d92cb2334b19751db851d221aab814cd9da1af Author: GeunSik,Lim Date: Thu May 21 14:31:17 2009 +0900 ftrace: fix typo 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 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: