linux-kernel - [PATCH v3 4/4] PM: hibernate: Support to select compression algorithm

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Date: Mon, 22 Jan 2024 18:45:28 +0530
From: Nikhil V <quic_nprakash@...cinc.com>
To: Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        "Jonathan
 Corbet" <corbet@....net>,
        "Rafael J. Wysocki" <rafael@...nel.org>
CC: Nikhil V <quic_nprakash@...cinc.com>,
        "Paul E. McKenney"
	<paulmck@...nel.org>, Tejun Heo <tj@...nel.org>,
        Yan-Jie Wang
	<yanjiewtw@...il.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        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: [PATCH v3 4/4] PM: hibernate: Support to select compression algorithm

Currently the default compression algorithm is selected based on
Kconfig. Introduce a kernel command line parameter "hib_compression" 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 offers better decompression speeds over a
default algorithm, which in turn reduces hibernation image restore time.

Users can set "hib_compression" command line parameter to override the
default algorithm. Currently LZO and LZ4 are the supported algorithms.
Usage:
    LZO: hib_compression=lzo
    LZ4: hib_compression=lz4

LZO is the default compression algorithm used with hibernation.

Signed-off-by: Nikhil V <quic_nprakash@...cinc.com>
---
 .../admin-guide/kernel-parameters.txt         |  6 ++++
 kernel/power/hibernate.c                      | 31 ++++++++++++++++++-
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 31b3a25680d0..22255bd9a4e3 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1748,6 +1748,12 @@
 				(that will set all pages holding image data
 				during restoration read-only).
 
+	hib_compression= [COMPRESSION ALGORITHM]
+		lzo		Select LZO compression algorithm to compress/decompress
+				hibernation images.
+		lz4		Select LZ4 compression algorithm to compress/decompress
+				hibernation images.
+
 	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
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 219191d6d0e8..75002fb3ad42 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -748,7 +748,8 @@ int hibernate(void)
 	 * Query for the compression algorithm support if compression is enabled.
 	 */
 	if (!nocompress) {
-		strscpy(hib_comp_algo, default_compressor, sizeof(hib_comp_algo));
+		if (!hib_comp_algo[0])
+			strscpy(hib_comp_algo, default_compressor, sizeof(hib_comp_algo));
 		if (crypto_has_comp(hib_comp_algo, 0, 0) != 1) {
 			pr_err("%s compression is not available\n", hib_comp_algo);
 			return -EOPNOTSUPP;
@@ -1422,6 +1423,33 @@ static int __init nohibernate_setup(char *str)
 	return 1;
 }
 
+static const char * const comp_alg_enabled[] = {
+#if IS_ENABLED(CONFIG_CRYPTO_LZO)
+	COMPRESSION_ALGO_LZO,
+#endif
+#if IS_ENABLED(CONFIG_CRYPTO_LZ4)
+	COMPRESSION_ALGO_LZ4,
+#endif
+};
+
+static int __init compression_setup(char *str)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(comp_alg_enabled); i++) {
+		if (!strcmp(str, comp_alg_enabled[i])) {
+			strscpy(hib_comp_algo, str, sizeof(hib_comp_algo));
+			goto setup_done;
+		}
+	}
+	pr_info("Cannot set specified compressor. Falling back to %s\n",
+		default_compressor);
+	strscpy(hib_comp_algo, default_compressor, sizeof(hib_comp_algo));
+
+setup_done:
+	return 1;
+}
+
 __setup("noresume", noresume_setup);
 __setup("resume_offset=", resume_offset_setup);
 __setup("resume=", resume_setup);
@@ -1429,3 +1457,4 @@ __setup("hibernate=", hibernate_setup);
 __setup("resumewait", resumewait_setup);
 __setup("resumedelay=", resumedelay_setup);
 __setup("nohibernate", nohibernate_setup);
+__setup("hib_compression=", compression_setup);
-- 
2.17.1