Re: [RFC PATCH v1] mm: improve call_controls_lock

Gutierrez Asier
2025-12-30T09:02:35Z

On 12/29/2025 6:22 PM, SeongJae Park wrote:
> Hello Asier,

Hi SeongJae,

>
> Thank you for sending this patch!
>
> On Mon, 29 Dec 2025 14:55:32 +0000 Asier Gutierrez <gutierrez.asier@huawei-partners.com> wrote:
>
>> This is a minor patch set for a call_controls_lock synchronization improvement.
>
> Please break description lines to not exceed 75 characters per line.
>
>>
>> Spinlocks are faster than mutexes, even when the mutex takes the fast
>> path. Hence, this patch replaces the mutex call_controls_lock with a spinlock.
>
> But call_controls_lock is not being used on performance critical part.
> Actually, most of DAMON code is not performance critical. I really appreciate
> your patch, but I have to say I don't think this change is really needed now.
> Please let me know if I'm missing something.

I was just reviewing the code and I noticed this. Yes, you are right, the performance
is not critical.

>>
>> Initial benchmarking shows the following results
>>
>>
>> # bpftrace -e 'kprobe:kdamond_call { @start[tid] = nsecs; }
>
> Commit log shouldn't start with '#'. Please consider indenting the above
> command and below outputs of it.
>
>
> Thanks,
> SJ
>
> [...]
>

Thanks a lot for the review!

--
Asier Gutierrez
Huawei