[PATCH] power: Changed CMP_THREADS from hardwired value to configurable value

[Jay Penny <hills.a.joel@gmail.com>]

From a873292405b37921d6a7428a7e9263f662e957cf Mon Sep 17 00:00:00 2001
From: Jay Penny <hills.a.joel@gmail.com>
Date: Fri, 14 Feb 2025 22:27:39 +1100
Subject: [PATCH] power: Changed CMP_THREADS from hardwired value to
 configurable value

I don't know what the rules are (unspoken or otherwise) for stating
that this is your patch - The CoC doesn't say anything regarding it,
so I'm just going to mention it here. This is my first kernel patch,
so if I mess something up, it's due to a lack of experience on my part.

Changed CMP_THREADS in kernel/power/swap.c from a hardwired 3 threads,
to a configurable one, and created a corresponding config option in
kernel/power/Kconfig.

The fact that this is such a simple change that hasn't been made yet
probably means that it shouldn't be made. That, or I'm just being
pessimistic.

Signed-off-by: Jay Penny <hills.a.joel@gmail.com>
---
 kernel/power/Kconfig | 13 +++++++++++++
 kernel/power/swap.c  |  2 +-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index ca947ed32e3d..432e75c76c49 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -80,6 +80,19 @@ config HIBERNATION
 
 	  For more information take a look at
<file:Documentation/power/swsusp.rst>.
 
+config HIBERNATION_THREADS
+	int "Hibernation threads"
+	depends on HIBERNATION
+	range 1 65535
+	default 3
+	help
+	  The maximum number of threads that should be used when
+	  compressing/decompressing a hibernation image. The number
+	  of threads used is calculated as:
+	  clamp(num_online_cpus() - 1, 1, HIBERNATION_THREADS).
+
+	  If in doubt, leave at the default of 3
+
 config HIBERNATION_SNAPSHOT_DEV
 	bool "Userspace snapshot device"
 	depends on HIBERNATION
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index 82b884b67152..6ac787f8421a 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -534,7 +534,7 @@ static int swap_writer_finish(struct
swap_map_handle *handle,
 #define CMP_SIZE	(CMP_PAGES * PAGE_SIZE)
 
 /* Maximum number of threads for compression/decompression. */
-#define CMP_THREADS	3
+#define CMP_THREADS	CONFIG_HIBERNATION_THREADS
 
 /* Minimum/maximum number of pages for read buffering. */
 #define CMP_MIN_RD_PAGES	1024
-- 
2.48.1