linux-kernel - Re: [RFC PATCH v2 0/3] sched/fair: introduce new scheduler group type group

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Message-ID: <e44c0761-ea50-4c44-b42c-415dffdb441d@linux.ibm.com>
Date: Thu, 20 Feb 2025 11:55:12 +0100
From: Tobias Huschle <huschle@...ux.ibm.com>
To: Shrikanth Hegde <sshegde@...ux.ibm.com>, linux-kernel@...r.kernel.org
Cc: mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        vschneid@...hat.com, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org
Subject: Re: [RFC PATCH v2 0/3] sched/fair: introduce new scheduler group type
 group_parked



On 18/02/2025 06:58, Shrikanth Hegde wrote:
[...]
>>
>> There are a couple of issues and corner cases which need further
>> considerations:
>> - rt & dl:      Realtime and deadline scheduling require some additional
>>                  attention.
> 
> I think we need to address atleast rt, there would be some non percpu 
> kworker threads which need to move out of parked cpus.
> 

Yea, sounds reasonable. Would probably make sense to go next for that one.

>> - ext:          Probably affected as well. Needs some conceptional
>>                  thoughts first.
>> - raciness:     Right now, there are no synchronization efforts. It needs
>>                  to be considered whether those might be necessary or if
>>                  it is alright that the parked-state of a CPU might 
>> change
>>                  during load-balancing.
>>
>> Patches apply to tip:sched/core
>>
>> The s390 patch serves as a simplified implementation example.
> 
> 
> Gave it a try on powerpc with the debugfs file. it works for 
> sched_normal tasks.
> 

That's great to hear!

>>
>> Tobias Huschle (3):
>>    sched/fair: introduce new scheduler group type group_parked
>>    sched/fair: adapt scheduler group weight and capacity for parked CPUs
>>    s390/topology: Add initial implementation for selection of parked CPUs
>>
>>   arch/s390/include/asm/smp.h    |   2 +
>>   arch/s390/kernel/smp.c         |   5 ++
>>   include/linux/sched/topology.h |  19 ++++++
>>   kernel/sched/core.c            |  13 ++++-
>>   kernel/sched/fair.c            | 104 ++++++++++++++++++++++++++++-----
>>   kernel/sched/syscalls.c        |   3 +
>>   6 files changed, 130 insertions(+), 16 deletions(-)
>>
>