2 SCHED_IDLE bugs in Cygwin 3.6

Eliot Moss moss@cs.umass.edu
Thu Dec 19 20:01:44 GMT 2024


On 12/19/2024 1:43 PM, Cedric Blancher via Cygwin wrote:
> On Thu, 19 Dec 2024 at 19:39, Eliot Moss <moss@cs.umass.edu> wrote:
>>
>> On 12/19/2024 11:38 AM, Cedric Blancher via Cygwin wrote:
>>> Good afternoon!
>>>
>>> 2 bugs with SCHED_IDLE support in Cygwin 3.6 after SCHED_IDLE support was added:
>>>
>>> 1. /bin/chrt does not list SCHED_IDLE
>>> $ chrt --max
>>> SCHED_OTHER min/max priority    : 0/0
>>> SCHED_FIFO min/max priority     : 1/32
>>> SCHED_RR min/max priority       : 1/32
>>>
>>> 2. Prio 0 does not work:
>>> chrt --idle 0 bash -c 'do something' gives an error in Cygwin 3.6, but
>>> works on Linux and other Oses
>>>
>>> Ced
>>
>> I wonder if this note from the man page is relevant:
>>
>> "Only SCHED_FIFO, SCHED_OTHER and SCHED_RR are part of POSIX 1003.1b Process Scheduling. The other scheduling attributes
>> may be ignored on some systems."
>>
>> Of course is SCHED_IDLE was advertised as being available, this does seem to be a bug (I see it on my system as well).
>>
>> I was able to use some commands under WSL (presumably more Linux-y), but none at all on Cygwin.
> 
> https://cygwin.com/git/?p=newlib-cygwin.git;a=commit;h=61c2f075cd55d4a52b4713383f75870c1e416923
> added SCHED_IDLE support for Cygwin 3.6. It should work.

Cygwin should support it, but I wonder if chrt (in util-linux) has been updated in light of the change.

Regards - Eliot Moss



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