linux-kernel - Re: [PATCH] PM: hibernate: make compression threads configurable via kernel parameter

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Message-ID: <CAJZ5v0j2Xa410LBfcKhxP3K1r0bpe6TU1FbnqXZJjUEJpubynQ@mail.gmail.com>
Date: Thu, 4 Sep 2025 21:37:19 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: luoxueqin <luoxueqin@...inos.cn>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, pavel@...nel.org, lenb@...nel.org, 
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PM: hibernate: make compression threads configurable via
 kernel parameter

On Thu, Aug 28, 2025 at 5:30 AM luoxueqin <luoxueqin@...inos.cn> wrote:
>
>
> 在 2025/8/26 19:43, Rafael J. Wysocki 写道:
> > On Tue, Aug 26, 2025 at 11:19 AM Xueqin Luo <luoxueqin@...inos.cn> wrote:
> >> A new kernel parameter 'cmp_threads=' is introduced to
> >> allow tuning the number of compression/decompression threads at boot.
> > And why is it useful/needed?
> The number of compression/decompression threads directly impacts
> hibernate and resume time.
> In our tests(averaged over 10 runs):
>      cmp_threads   hibernate(s)   resume(s)
>              3                           12.14          18.86
>              4                           12.28          17.48
>              5                           11.09          16.77
>              6                           11.08          16.44
> With 5–6 threads, resume latency improves by ~12% compared to 3 threads.
> But on low-core systems,
> more threads may cause contention. Making it configurable allows
> integrators to balance performance
>   and CPU usage across different hardware without recompiling the kernel.

So please add this information to the changelog of the patch and resend it.

Thanks!