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From:   Nikhil V <quic_nprakash@quicinc.com>
To:     Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
        "Jonathan Corbet" <corbet@lwn.net>,
        "Rafael J. Wysocki" <rafael@kernel.org>
CC:     Nikhil V <quic_nprakash@quicinc.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        "Peter Zijlstra" <peterz@infradead.org>,
        "Steven Rostedt (Google)" <rostedt@goodmis.org>,
        "Paul E. McKenney" <paulmck@kernel.org>, Tejun Heo <tj@kernel.org>,
        <linux-kernel@vger.kernel.org>, <linux-doc@vger.kernel.org>,
        <linux-pm@vger.kernel.org>, <quic_pkondeti@quicinc.com>,
        <quic_kprasan@quicinc.com>, <quic_mpilaniy@quicinc.com>,
        <quic_shrekk@quicinc.com>, <mpleshivenkov@google.com>,
        <ericyin@google.com>
Subject: [RFC PATCH 4/4] PM: hibernate: Support to select compression algorithm
Date:   Tue, 26 Sep 2023 14:27:14 +0530
Message-ID: <b49a7bdd957bf86913700220b6c1f8f12c753b52.1695711299.git.quic_nprakash@quicinc.com>
In-Reply-To: <cover.1695711299.git.quic_nprakash@quicinc.com>
References: <cover.1695711299.git.quic_nprakash@quicinc.com>
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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@quicinc.com>
---
 .../admin-guide/kernel-parameters.txt         |  6 ++++
 kernel/power/hibernate.c                      | 29 ++++++++++++++++++-
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 0a1731a0f0ef..3f5f3e453db1 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1734,6 +1734,12 @@
 				(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 87be8cda9b9b..22296a7b640c 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -742,7 +742,8 @@ 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;
@@ -1416,6 +1417,31 @@ 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;
+		}
+	}
+	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);
@@ -1423,3 +1449,4 @@ __setup("hibernate=", hibernate_setup);
 __setup("resumewait", resumewait_setup);
 __setup("resumedelay=", resumedelay_setup);
 __setup("nohibernate", nohibernate_setup);
+__setup("hib_compression=", compression_setup);
-- 
2.17.1