linux-kernel - Re: [RFC PATCH v1] mm: improve call_controls

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Message-ID: <4b367446-2248-4936-99b6-e9ee93298eb5@huawei-partners.com>
Date: Tue, 30 Dec 2025 12:02:31 +0300
From: Gutierrez Asier <gutierrez.asier@...wei-partners.com>
To: SeongJae Park <sj@...nel.org>
CC: <akpm@...ux-foundation.org>, <damon@...ts.linux.dev>,
	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
	<wangkefeng.wang@...wei.com>, <artem.kuzin@...wei.com>,
	<stepanov.anatoly@...wei.com>
Subject: Re: [RFC PATCH v1] mm: improve call_controls_lock



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@...wei-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