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

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

Hi Benno, Karel

On 18/06/25 14:55, Karel Zak wrote:
> On Wed, Jun 18, 2025 at 11:18:18AM +0200, 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?
> 
> Ah, I now read Benno's note more carefully. The code just silently ignores  
> policy when priority is not specified.
> 
> $ chrt --fifo --pid $$  
> pid 994013's current scheduling policy: SCHED_OTHER  
> pid 994013's current scheduling priority: 0
> 
> This is ugly. The question is how important it is to support this for  
> backward compatibility. I'd assume that users use "chrt --pid $$" to get  
> the current setting.
> 

chrt --pid 20570
pid 20570's current scheduling policy: SCHED_OTHER
pid 20570's current scheduling priority: 0
pid 20570's current runtime parameter: 2800000

After this patch also, we still get the current setting. Can you give it
a try with the patch applied? Let me know if I am missing something.

Thanks for taking a look.

Thanks,
Madadi Vineeth Reddy

>     Karel
>