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

From: Nikhil V
Date: Wed Feb 14 2024 - 02:04:13 EST




On 2/13/2024 12:34 AM, Randy Dunlap wrote:


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@xxxxxxxxxxx>
---
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@xxxxxxxxxxx/
[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.

Hi @Randy,

Will update the documentation as mentioned and send the patch for review.

Thanks,
Nikhil V