linux-kernel - Re: [PATCH] PM: hibernate: Support to select compression algorithm

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Date: Mon, 12 Feb 2024 11:04:24 -0800
From: Randy Dunlap <rdunlap@...radead.org>
To: Nikhil V <quic_nprakash@...cinc.com>, Pavel Machek <pavel@....cz>,
 Len Brown <len.brown@...el.com>, Jonathan Corbet <corbet@....net>,
 "Rafael J. Wysocki" <rafael@...nel.org>
Cc: "Paul E. McKenney" <paulmck@...nel.org>, Tejun Heo <tj@...nel.org>,
 Yan-Jie Wang <yanjiewtw@...il.com>, Peter Zijlstra <peterz@...radead.org>,
 "Steven Rostedt (Google)" <rostedt@...dmis.org>,
 Catalin Marinas <catalin.marinas@....com>, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
 quic_pkondeti@...cinc.com, quic_kprasan@...cinc.com,
 quic_mpilaniy@...cinc.com, quic_shrekk@...cinc.com,
 mpleshivenkov@...gle.com, ericyin@...gle.com
Subject: Re: [PATCH] PM: hibernate: Support to select compression algorithm



On 2/12/24 04:32, Nikhil V wrote:
> Currently the default compression algorithm is selected based on
> compile time options. Introduce a module parameter "hibernate.compressor"
> to override this behaviour.
> 
> Different compression algorithms have different characteristics and
> hibernation may benefit when it uses any of these algorithms, especially
> when a secondary algorithm(LZ4) offers better decompression speeds over a
> default algorithm(LZO), which in turn reduces hibernation image restore
> time.
> 
> Users can override the default algorithm in two ways:
>  1) Passing "hibernate.compressor" as kernel command line parameter.
>     Usage:
>     	LZO: hibernate.compressor=lzo
>     	LZ4: hibernate.compressor=lz4
> 
>  2) Specifying the algorithm at runtime.
>     Usage:
> 	LZO: echo lzo > /sys/module/hibernate/parameters/compressor
> 	LZ4: echo lz4 > /sys/module/hibernate/parameters/compressor
> 
> Currently LZO and LZ4 are the supported algorithms. LZO is the default
> compression algorithm used with hibernation.
> 
> Signed-off-by: Nikhil V <quic_nprakash@...cinc.com>
> ---
> This patch is dependent on the patch series, [1] (patches 1/4 to 3/4).
> This is picked in linux-next, [2].
>  [1] https://lore.kernel.org/all/cover.1705927916.git.quic_nprakash@quicinc.com/
>  [2] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/log/kernel/power?h=next-20240212
> 
>  .../admin-guide/kernel-parameters.txt         | 10 ++++
>  kernel/power/hibernate.c                      | 57 ++++++++++++++++++-
>  2 files changed, 64 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 31b3a25680d0..522155056645 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1748,6 +1748,16 @@
>  				(that will set all pages holding image data
>  				during restoration read-only).
>  

Hi,
Please add something like:


> +	hibernate.compressor= 	[HIBERNATION] Compression algorithm to be
> +				used with hibernation.
> +				Format: { lzo | lz4 }
				Default: lzo
> +
> +				lzo: Select LZO compression algorithm to
> +				compress/decompress hibernation image.
> +
> +				lz4: Select LZ4 compression algorithm to
> +				compress/decompress hibernation image.
> +
>  	highmem=nn[KMG]	[KNL,BOOT] forces the highmem zone to have an exact
>  			size of <nn>. This works even on boxes that have no
>  			highmem otherwise. This also works to reduce highmem


thanks.
-- 
#Randy