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Message-ID: <alpine.DEB.2.00.0905211213520.4632@gandalf.stny.rr.com>
Date: Thu, 21 May 2009 12:14:14 -0400 (EDT)
From: Steven Rostedt <rostedt@...dmis.org>
To: GeunSik Lim <leemgs1@...il.com>
cc: Ingo Molnar <mingo@...e.hu>, williams <williams@...hat.com>,
tglx <tglx@...utronix.de>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
linux-rt-users <linux-rt-users@...r.kernel.org>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1 ,v3] ftrace: fix typo in ftrace.txt file
On Thu, 21 May 2009, GeunSik Lim wrote:
>
> --
>
> commit 16d92cb2334b19751db851d221aab814cd9da1af
> Author: GeunSik,Lim <leemgs1@...il.com>
> 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 <geunsik.lim@...sung.com>
>
> 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:
Acked-by: Steven Rostedt <rostedt@...dmis.org>
Thanks,
-- Steve
--
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