Commit 3fec6e59 authored by Nikhil V's avatar Nikhil V Committed by Rafael J. Wysocki
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PM: hibernate: Support to select compression algorithm 



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: default avatarNikhil V <quic_nprakash@quicinc.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 9bb6c395

Documentation/admin-guide/kernel-parameters.txt

+11 −0
Original line number Diff line number Diff line
@@ -1748,6 +1748,17 @@ 
				(that will set all pages holding image data

				during restoration read-only).



	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

kernel/power/hibernate.c

+54 −3
Original line number Diff line number Diff line
@@ -47,7 +47,7 @@ dev_t swsusp_resume_device; 
sector_t swsusp_resume_block;

__visible int in_suspend __nosavedata;



static const char *default_compressor = CONFIG_HIBERNATION_DEF_COMP;

static char hibernate_compressor[CRYPTO_MAX_ALG_NAME] = CONFIG_HIBERNATION_DEF_COMP;



/*

 * Compression/decompression algorithm to be used while saving/loading
@@ -748,7 +748,7 @@ 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));

		strscpy(hib_comp_algo, hibernate_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;
@@ -999,7 +999,7 @@ static int software_resume(void) 
		if (swsusp_header_flags & SF_COMPRESSION_ALG_LZ4)

			strscpy(hib_comp_algo, COMPRESSION_ALGO_LZ4, sizeof(hib_comp_algo));

		else

			strscpy(hib_comp_algo, default_compressor, sizeof(hib_comp_algo));

			strscpy(hib_comp_algo, COMPRESSION_ALGO_LZO, 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);

			error = -EOPNOTSUPP;
@@ -1422,6 +1422,57 @@ 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 hibernate_compressor_param_set(const char *compressor,

		const struct kernel_param *kp)

{

	unsigned int sleep_flags;

	int index, ret;



	sleep_flags = lock_system_sleep();



	index = sysfs_match_string(comp_alg_enabled, compressor);

	if (index >= 0) {

		ret = param_set_copystring(comp_alg_enabled[index], kp);

		if (!ret)

			strscpy(hib_comp_algo, comp_alg_enabled[index],

				sizeof(hib_comp_algo));

	} else {

		ret = index;

	}



	unlock_system_sleep(sleep_flags);



	if (ret)

		pr_debug("Cannot set specified compressor %s\n",

			 compressor);



	return ret;

}



static const struct kernel_param_ops hibernate_compressor_param_ops = {

	.set    = hibernate_compressor_param_set,

	.get    = param_get_string,

};



static struct kparam_string hibernate_compressor_param_string = {

	.maxlen = sizeof(hibernate_compressor),

	.string = hibernate_compressor,

};



module_param_cb(compressor, &hibernate_compressor_param_ops,

		&hibernate_compressor_param_string, 0644);

MODULE_PARM_DESC(compressor,

		 "Compression algorithm to be used with hibernation");



__setup("noresume", noresume_setup);

__setup("resume_offset=", resume_offset_setup);

__setup("resume=", resume_setup);