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

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Message-ID: <20251229152250.78975-1-sj@kernel.org>
Date: Mon, 29 Dec 2025 07:22:49 -0800
From: SeongJae Park <sj@...nel.org>
To: Asier Gutierrez <gutierrez.asier@...wei-partners.com>
Cc: SeongJae Park <sj@...nel.org>,
	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

Hello Asier,

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.

> 
> 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

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