Re: [PATCH v2] chrt: Make priority optional for policies that don't use it

[Madadi Vineeth Reddy <vineethr@linux.ibm.com>]

On 18/06/25 14:48, Karel Zak wrote:
> On Wed, Jun 18, 2025 at 10:18:29AM +0200, Benno Schulenberg wrote:
>>
>> Op 17-06-2025 om 20:24 schreef Madadi Vineeth Reddy:
>>> Currently, chrt requires a priority argument even for scheduling
>>> policies like SCHED_OTHER and SCHED_BATCH, which ignore it.
>>>
>>> This change relaxes that requirement. Now, priority is only expected
>>> for SCHED_FIFO and SCHED_RR. For other policies, a default value of 0
>>> is set internally and no argument is required on the command line.
>>
>> Doesn't this alter the "show-the-current-policy-and-priority" behavior
>> when no priority is given?  Currently `./chrt --help` says (trimmed):
>  
> Very good point. The priority policy (--{other,...}) should be
> required to ensure that the user wants to alter the setting rather
> than print the current situation. Madadi, what do you think?
> 
>>   Set policy:
>>    chrt [options] --pid <priority> <pid>
>>
>>   Get policy:
>>    chrt [options] -p <pid>
> 
> I really don't like the use of "-p." We should use "--pid" everywhere  
> (in --help, man page, and examples).

I can spin off a separate patch to consistently use --pid instead of -p
in the help text, man page, and examples.

Thanks,
Madadi Vineeth Reddy

> 
>> Without the proposed change, running `chrt --other --pid $$` says:
>>
>>   pid 1427's current scheduling policy: SCHED_OTHER
>>   pid 1427's current scheduling priority: 0
>>
>> After the change, that same command outputs nothing.  Maybe that is
>> fine, but it would require some adjustment of the docs.
> 
> This is bug.
> 
>     Karel
>