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Message-ID: <CAJZ5v0iMsqCguCWytVZugVN15z6+zrNiSSuK3XPSO8Oqdh3N8A@mail.gmail.com>
Date: Thu, 22 Feb 2024 20:04:23 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Nikhil V <quic_nprakash@...cinc.com>
Cc: Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>, Jonathan Corbet <corbet@....net>,
"Rafael J. Wysocki" <rafael@...nel.org>, "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: Re: [PATCH v2] PM: hibernate: Support to select compression algorithm
On Wed, Feb 14, 2024 at 8:40 AM Nikhil V <quic_nprakash@...cinc.com> wrote:
>
> 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: Nikhil V <quic_nprakash@...cinc.com>
> ---
> This patch is dependent on the patch series, [1] (patches 1/4 to 3/4).
> This is picked in linux-next, [2].
> [1] https://lore.kernel.org/all/cover.1705927916.git.quic_nprakash@quicinc.com/
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/log/kernel/power?h=next-20240212
>
> Changes in v2:
> Changes to incorporate suggestions from Randy Dunlap:
> - Update documentation to specify the default compression algorithm.
> Link to v1:
> https://lore.kernel.org/all/3776355f920c1af44490e076072f93bafdf128cc.1707740870.git.quic_nprakash@quicinc.com/
>
> .../admin-guide/kernel-parameters.txt | 11 ++++
> kernel/power/hibernate.c | 57 ++++++++++++++++++-
> 2 files changed, 65 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 31b3a25680d0..8f7fb911b2cc 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -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
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index 219191d6d0e8..43b1a82e800c 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -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);
> --
Applied as 6.9 material, thanks!
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