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SubjectRe: [PATCH RESEND v2 0/4] PM: hibernate: LZ4 compression support
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On 11/15/2023 5:52 PM, Nikhil V wrote:
> This patch series covers the following:
> 1. Renaming lzo* to generic names, except for lzo_xxx() APIs. This is
> used in the next patch where we move to crypto based APIs for
> compression. There are no functional changes introduced by this
> approach.
>
>
> 2. Replace LZO library calls with crypto generic APIs
>
> Currently for hibernation, LZO is the only compression algorithm
> available and uses the existing LZO library calls. However, there
> is no flexibility to switch to other algorithms which provides better
> results. The main idea is that different compression algorithms have
> different characteristics and hibernation may benefit when it uses
> alternate algorithms.
>
> By moving to crypto based APIs, it lays a foundation to use other
> compression algorithms for hibernation.
>
>
> 3. LZ4 compression
>
> Extend the support for LZ4 compression to be used with hibernation.
> The main idea is that different compression algorithms have different
> characteristics and hibernation may benefit when it uses any of these
> algorithms: a default algorithm, having higher compression rate but is
> slower(compression/decompression) and a secondary algorithm, that is
> faster(compression/decompression) but has lower compression rate.
>
> LZ4 algorithm has better decompression speeds over LZO. This reduces
> the hibernation image restore time.
> As per test results:
> LZO LZ4
> Size before Compression(bytes) 682696704 682393600
> Size after Compression(bytes) 146502402 155993547
> Decompression Rate 335.02 MB/s 501.05 MB/s
> Restore time 4.4s 3.8s
>
> LZO is the default compression algorithm used for hibernation. Enable
> CONFIG_HIBERNATION_DEF_COMP_LZ4 to set the default compressor as LZ4.
>
> Compression Benchmarks: https://github.com/lz4/lz4
>
>
> 4. 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.
>
> Users can set "hib_compression" command line parameter to specify
> the algorithm.
> Usage:
> LZO: hib_compression=lzo
> LZ4: hib_compression=lz4
> LZO is the default compression algorithm used with hibernation.
>
>
> Changes in v2:
> - Fixed build issues reported by kernel test robot for ARCH=sh, [1].
> [1] https://lore.kernel.org/oe-kbuild-all/202310171226.pLUPeuC7-lkp@intel.com/
>
> Nikhil V (4):
> PM: hibernate: Rename lzo* to make it generic
> PM: hibernate: Move to crypto APIs for LZO compression
> PM: hibernate: Add support for LZ4 compression for hibernation
> PM: hibernate: Support to select compression algorithm
>
> .../admin-guide/kernel-parameters.txt | 6 +
> kernel/power/Kconfig | 26 ++-
> kernel/power/hibernate.c | 85 +++++++-
> kernel/power/power.h | 19 ++
> kernel/power/swap.c | 189 +++++++++++-------
> 5 files changed, 251 insertions(+), 74 deletions(-)
>
>
> base-commit: b85ea95d086471afb4ad062012a4d73cd328fa86

Hi @Rafael/@Pavel/@Len,

Could you please let me know if you have any concerns on this approach?

FYI: We have tested this on QEMU and its working fine.

Logs(suspend):
[ 75.242227] PM: Using 3 thread(s) for lz4 compression
[ 75.243043] PM: Compressing and saving image data (17495 pages)...
[ 75.243917] PM: Image saving progress: 0%
[ 75.261727] PM: Image saving progress: 10%
[ 75.277968] PM: Image saving progress: 20%
[ 75.290927] PM: Image saving progress: 30%
[ 75.305186] PM: Image saving progress: 40%
[ 75.318252] PM: Image saving progress: 50%
[ 75.330310] PM: Image saving progress: 60%
[ 75.345906] PM: Image saving progress: 70%
[ 75.359054] PM: Image saving progress: 80%
[ 75.372176] PM: Image saving progress: 90%
[ 75.388411] PM: Image saving progress: 100%
[ 75.389775] PM: Image saving done
[ 75.390397] PM: hibernation: Wrote 69980 kbytes in 0.14 seconds
(499.85 MB/s)
[ 75.391591] PM: Image size after compression: 28242 kbytes
[ 75.393089] PM: S|
[ 75.399784] sd 0:0:0:0: [sda] Synchronizing SCSI cache
[ 75.439170] sd 0:0:0:0: [sda] Stopping disk
[ 75.501461] ACPI: PM: Preparing to enter system sleep state S5
[ 75.502766] reboot: Power down



Logs(resume):
[ 1.063248] PM: hibernation: resume from hibernation
[ 1.072868] Freezing user space processes
[ 1.073707] Freezing user space processes completed (elapsed 0.000
seconds)
[ 1.075192] OOM killer disabled.
[ 1.075837] Freezing remaining freezable tasks
[ 1.078010] Freezing remaining freezable tasks completed (elapsed
0.001 seconds)
[ 1.087489] PM: Using 3 thread(s) for lz4 decompression
[ 1.088570] PM: Loading and decompressing image data (17495 pages)...
[ 1.125549] PM: Image loading progress: 0%
[ 1.190380] PM: Image loading progress: 10%
[ 1.204963] PM: Image loading progress: 20%
[ 1.218988] PM: Image loading progress: 30%
[ 1.233697] PM: Image loading progress: 40%
[ 1.248658] PM: Image loading progress: 50%
[ 1.262910] PM: Image loading progress: 60%
[ 1.276966] PM: Image loading progress: 70%
[ 1.290517] PM: Image loading progress: 80%
[ 1.305427] PM: Image loading progress: 90%
[ 1.320666] PM: Image loading progress: 100%
[ 1.321866] PM: Image loading done
[ 1.322599] PM: hibernation: Read 69980 kbytes in 0.23 seconds
(304.26 MB/s)
[ 1.324795] printk: Suspending console(s) (use no_console_suspend to
debug)
[ 74.943801] ata1.00: Entering standby power mode


Thanks,
Nikhil V

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