[PATCH 1/1] ftrace: fix typo in ftrace.txt file

[PATCH 1/1] ftrace: fix typo in ftrace.txt file

[GeunSik Lim]

[-- Attachment #1: Type: text/plain, Size: 2028 bytes --]



commit 43bf3fdddfd6b0ac65ef59bec3c79d9f9064e8bd
Author: GeunSik,Lim <leemgs1@gmail.com>
Date:   Thu May 14 13:39:18 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 static priority in the range 1 to 99.
    
        Signed-off-by: GeunSik Lim <geunsik.lim@samsung.com>

diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index fd9a3e6..0e17632 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -518,9 +518,14 @@ 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 priority: 0(high) to 99(low)    ==> user RT priority 99(high) to 1(low)
+ Kernel priority: 100(high) to 139(low) ==> user nice -20(high) to 19(low)
+ Kernel priority: 140                   ==> idle task priority
+
+Processes scheduled with SCHED_OTHER or SCHED_BATCH must be assigned
+the static priority 0. Processes scheduled under SCHED_FIFO or SCHED_RR 
+can have a static priority in the range 1 to 99. 
+ (reference: $> man 2 sched_setscheduler)
 
 The task states are:
 


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GeunSik Lim (ELS - OS Group - S/W Lab - SAIT - SAMSUNG)
e-Mail  :1) geunsik.lim@samsung.com
         2) leemgs@gmail.com , leemgs1@gmail.com
HomePage: http://intomail.dnip.net/invain/me/
-----------------------------------------------

[-- Attachment #2: fix-typo-chart-map-priority-ftrace.patch --]
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commit 43bf3fdddfd6b0ac65ef59bec3c79d9f9064e8bd
Author: GeunSik,Lim <leemgs1@gmail.com>
Date:   Thu May 14 13:39:18 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 static priority in the range 1 to 99.
    
        Signed-off-by: GeunSik Lim <geunsik.lim@samsung.com>

diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index fd9a3e6..0e17632 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -518,9 +518,14 @@ 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 priority: 0(high) to 99(low)    ==> user RT priority 99(high) to 1(low)
+ Kernel priority: 100(high) to 139(low) ==> user nice -20(high) to 19(low)
+ Kernel priority: 140                   ==> idle task priority
+
+Processes scheduled with SCHED_OTHER or SCHED_BATCH must be assigned
+the static priority 0. Processes scheduled under SCHED_FIFO or SCHED_RR 
+can have a static priority in the range 1 to 99. 
+ (reference: $> man 2 sched_setscheduler)
 
 The task states are:
 

Re: [PATCH 1/1] ftrace: fix typo in ftrace.txt file

[Steven Rostedt]

On Wed, 20 May 2009, GeunSik Lim wrote:

> 
> 
> commit 43bf3fdddfd6b0ac65ef59bec3c79d9f9064e8bd
> Author: GeunSik,Lim <leemgs1@gmail.com>
> Date:   Thu May 14 13:39:18 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 static priority in the range 1 to 99.
>     
>         Signed-off-by: GeunSik Lim <geunsik.lim@samsung.com>
> 
> diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
> index fd9a3e6..0e17632 100644
> --- a/Documentation/trace/ftrace.txt
> +++ b/Documentation/trace/ftrace.txt
> @@ -518,9 +518,14 @@ 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 priority: 0(high) to 99(low)    ==> user RT priority 99(high) to 1(low)

Shouldn't that be:

 Kernel priority: 0(high) to 98(low)    ==> user RT priority 99(high) to 1(low)

100 items does not map to 99. Which begs the question, what can have 
internal kernel priority 99?

> + Kernel priority: 100(high) to 139(low) ==> user nice -20(high) to 19(low)
> + Kernel priority: 140                   ==> idle task priority
> +
> +Processes scheduled with SCHED_OTHER or SCHED_BATCH must be assigned
> +the static priority 0. Processes scheduled under SCHED_FIFO or SCHED_RR 

This line is confusing. "static priorty 0" really has no meaning here. 
Those now enter the "nice" priorities, and this statement does not 
represent what is shown in the ftrace output.

> +can have a static priority in the range 1 to 99. 
> + (reference: $> man 2 sched_setscheduler)
>  

-- Steve

Re: [PATCH 1/1] ftrace: fix typo in ftrace.txt file

[GeunSik Lim]

2009/5/20 Steven Rostedt <rostedt@goodmis.org>:
>
> On Wed, 20 May 2009, GeunSik Lim wrote:
>
>>
>>
>> commit 43bf3fdddfd6b0ac65ef59bec3c79d9f9064e8bd
>> Author: GeunSik,Lim <leemgs1@gmail.com>
>> Date:   Thu May 14 13:39:18 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 static priority in the range 1 to 99.
>>
>>         Signed-off-by: GeunSik Lim <geunsik.lim@samsung.com>
>>
>> diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
>> index fd9a3e6..0e17632 100644
>> --- a/Documentation/trace/ftrace.txt
>> +++ b/Documentation/trace/ftrace.txt
>> @@ -518,9 +518,14 @@ 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 priority: 0(high) to 99(low)    ==> user RT priority 99(high) to 1(low)
>
> Shouldn't that be:
>
>  Kernel priority: 0(high) to 98(low)    ==> user RT priority 99(high) to 1(low)
>
Thank you for your opinion.  I think about corrected expression for
quick chart to map between kernel space and user space in ftrace .

> 100 items does not map to 99. Which begs the question, what can have
> internal kernel priority 99?
>
ok.  Below example is about  kernel (static) priority 99 that you said.
please, refer to
http://www.kernel.org/doc/man-pages/online/pages/man2/sched_setscheduler.2.html
 webpage.

 For processes scheduled under one of the normal scheduling policies
(SCHED_OTHER, SCHED_IDLE, SCHED_BATCH), sched_priority is not used in
 scheduling decisions (it must be specified as 0).


int main (int argc, char **argv)
{	int pidnumber, ret;
	struct sched_param p;
	p.sched_priority = 0; <------ Kernel (static) priority.
	if (argc != 2) {
		printf("usage: setbatch <pid>\n");
		exit(-1);
	}
	pidnumber = atol(argv[1]);
         /* 3 = Number of SCHED_BATCH Constant */
	ret = sched_setscheduler(pidnumber, 3, &p);
	if (ret) {
		printf("could not set pid %d to SCHED_BATCH: err %d.\n", pid, ret);
		return -1;
	}
	printf("pid %d is SCHED_BATCH from now on.\n", pid);
	return 0;
}


>> + Kernel priority: 100(high) to 139(low) ==> user nice -20(high) to 19(low)
>> + Kernel priority: 140                   ==> idle task priority
>> +
>> +Processes scheduled with SCHED_OTHER or SCHED_BATCH must be assigned
>> +the static priority 0. Processes scheduled under SCHED_FIFO or SCHED_RR
>
> This line is confusing. "static priorty 0" really has no meaning here.
> Those now enter the "nice" priorities, and this statement does not
> represent what is shown in the ftrace output.
>
I agree with your opinion about exact understanding of ftrace output.
I will remove this additional description to avoid confusing
when we use this document as ftrace how to.

>> +can have a static priority in the range 1 to 99.
>> + (reference: $> man 2 sched_setscheduler)
>>
>
> -- Steve
>
>



-- 
Regards,
GeunSik Lim
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