[RFC 2/6] PM: Hibernate: Add option to disable disk offset randomization

Vivek Kumar
2022-05-18T07:49:25Z

Add a kernel parameter to disable the disk offset randomization
for SSD devices in which such feature is available at the
firmware level. This is helpful in improving hibernation
resume time.

Signed-off-by: Vivek Kumar <quic_vivekuma@quicinc.com>
Signed-off-by: Prasanna Kumar <quic_kprasan@quicinc.com>
---
Documentation/admin-guide/kernel-parameters.txt | 11 +++++++++++
kernel/power/swap.c | 9 +++++++++
2 files changed, 20 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 666ade9..06b4f10 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5192,6 +5192,17 @@
Useful for devices that are detected asynchronously
(e.g. USB and MMC devices).

+ noswap_randomize
+ Kernel uses random disk offsets to help with wear-levelling
+ of SSD devices, while saving the hibernation snapshot image to
+ disk. Use this parameter to disable this feature for SSD
+ devices in scenarios when, such randomization is addressed at
+ the firmware level and hibenration image is not re-generated
+ frequently.
+ (Useful for improving hibernation resume time as snapshot pages
+ are available in disk serially and can be read in bigger chunks
+ without seeking)
+
retain_initrd [RAM] Keep initrd memory after extraction

rfkill.default_state=
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index 91fffdd..8d5c811 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -44,6 +44,7 @@ u32 swsusp_hardware_signature;
*/
static bool clean_pages_on_read;
static bool clean_pages_on_decompress;
+static bool noswap_randomize;

/*
* The swap map is a data structure used for keeping track of each page
@@ -1616,3 +1617,11 @@ static int __init swsusp_header_init(void)
}

core_initcall(swsusp_header_init);
+
+static int __init noswap_randomize_setup(char *str)
+{
+ noswap_randomize = true;
+ return 1;
+}
+
+__setup("noswap_randomize", noswap_randomize_setup);
--
2.7.4