Re: [PATCH 1/5] sched/psi: Make psi stubs consistent for !CONFIG_PSI

[K Prateek Nayak <kprateek.nayak@amd.com>]

Hello Vineeth,

On 11/20/2025 11:29 AM, Madadi Vineeth Reddy wrote:
> On 18/11/25 00:25, K Prateek Nayak wrote:
>> commit 1a6151017ee5 ("sched: psi: pass enqueue/dequeue flags to psi
>> callbacks directly") modified the psi_enqueue() and psi_dequeue()
>> functions to take the complete enqueue/dequeue flags but left the stubs
>> for !CONFIG_PSI unaltered.
>>
>> Modify the stubs to also accept the flags argument to keep it consistent
>> with CONFIG_PSI.
>>
>> Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
>> ---
>>  kernel/sched/stats.h | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
>> index cbf7206b3f9d..3323d773fec3 100644
>> --- a/kernel/sched/stats.h
>> +++ b/kernel/sched/stats.h
>> @@ -221,8 +221,8 @@ static inline void psi_sched_switch(struct task_struct *prev,
>>  }
>>  
>>  #else /* !CONFIG_PSI: */
>> -static inline void psi_enqueue(struct task_struct *p, bool migrate) {}
>> -static inline void psi_dequeue(struct task_struct *p, bool migrate) {}
>> +static inline void psi_enqueue(struct task_struct *p, int flags) {}
>> +static inline void psi_dequeue(struct task_struct *p, int flags) {}
>>  static inline void psi_ttwu_dequeue(struct task_struct *p) {}
>>  static inline void psi_sched_switch(struct task_struct *prev,
>>  				    struct task_struct *next,
> 
> Right. The commit that updated the function signature did not update the
> !CONFIG_PSI stubs accordingly. This patch corrects that.
> 
> Reviewed-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>

Thanks for the review.

P.S. John has an alternate fix for the same at
https://lore.kernel.org/lkml/20251118055242.4030849-1-jstultz@google.com/

That considers a blocked donor as a runnable entity from PSI
standpoint.

This series implements the alternate approach of blocking the PSI signals
when the blocked donor is retained on the rq, skipping the block_task()
and it enqueues the PSI signal back when the donor is woken up again.

-- 
Thanks and Regards,
Prateek