Re: [PATCH RESEND v2 0/4] PM: hibernate: LZ4 compression support

[Nikhil V]

On 1/22/2024 5:46 PM, Rafael J. Wysocki wrote:
> On Mon, Jan 22, 2024 at 1:14 PM Nikhil V <quic_nprakash@xxxxxxxxxxx> wrote:
> > On 12/12/2023 6:14 PM, Rafael J. Wysocki wrote:
> > > Hi,
> > >
> > > On Wed, Nov 29, 2023 at 11:20 AM Nikhil V <quic_nprakash@xxxxxxxxxxx> wrote:
> > > > 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@xxxxxxxxx/
> > > > >
> > > > > 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?
> > >
> > > Not really a concern, but that is a significant change that I would
> > > rather make early in the cycle, which means after the 6.8 merge
> > > window.
> > >
> > > No need to resend unless there is something to address in which case
> > > I'll let you know.
> > >
> > > Thanks!
> > >
> > > > 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
> >
> >
> > Hi @Rafael
> >
> > We have picked this patch series on 6.8-rc1 and tested the functionality
> > on QEMU. Its working fine. However, while applying the patches we could
> > see minor conflicts. Could you please let me know if we need to push a
> > new version after resolving these conflicts?
>
> It will help.
>
> I can resolve the conflicts, but I may make mistakes in the process.
>
> Thanks!

Thanks for the response. Will push a new version after resolving the 
conflicts.

Thanks,
Nikhil V