[RFC,0/4] PM: hibernate: LZ4 compression support

  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.

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                          |  25 ++-
 kernel/power/hibernate.c                      |  83 +++++++-
 kernel/power/power.h                          |  19 ++
 kernel/power/swap.c                           | 189 +++++++++++-------
 5 files changed, 248 insertions(+), 74 deletions(-)
  

On 9/26/2023 2:27 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.
> 
> 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                          |  25 ++-
>   kernel/power/hibernate.c                      |  83 +++++++-
>   kernel/power/power.h                          |  19 ++
>   kernel/power/swap.c                           | 189 +++++++++++-------
>   5 files changed, 248 insertions(+), 74 deletions(-)
> 

Hi,

Could you please let me know if you have any concerns/comments on this 
approach? If there are no comments, I could push another patch series 
with PATCH tag for review.

Thanks
Nikhil V
  

On Tue, Sep 26, 2023 at 02:27:10PM +0530, 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.
> 
> 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                          |  25 ++-
>  kernel/power/hibernate.c                      |  83 +++++++-
>  kernel/power/power.h                          |  19 ++
>  kernel/power/swap.c                           | 189 +++++++++++-------
>  5 files changed, 248 insertions(+), 74 deletions(-)
> 

I have tested this series on x86 QEMU with v6.6-rc3 (plus another patch
from pm-next tree i.e "PM: hibernate: use __get_safe_page() rather than
touching the list"). It works as advertised.

Thanks,
Pavan