On 1/31/2024 7:50 PM, Rafael J. Wysocki wrote:
On Mon, Jan 22, 2024 at 2:16 PM Nikhil V <quic_nprakash@xxxxxxxxxxx> 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 v3:
- Rebased to v6.8-rc1 after resolving the minor conflicts.
- Link to v2:
https://lore.kernel.org/all/cover.1700048610.git.quic_nprakash@xxxxxxxxxxx/
I've applied the first 3 patches in the series (as 6.9 material), but
I'm not particularly happy with the last one.
First off, I'm not sure if a kernel command line parameter is the most
convenient way of selecting the compression algorithm. Since (AFAICS)
the restore kernel will detect the compression algo in use anyway (or
at least it can be made do so), a modparam should work for this and it
would be far more convenient to use.
Second, if I can be convinced that indeed, using a kernel command line
option for this is the way to go, I don't particularly like the name
used in that patch.
Please feel free to send a replacement for patch [4/4] separately.
Thanks!
Hi @Rafael,
Thanks for the update.
Regarding patch[4/4], will work on modifying the code as mentioned by
adding module parameter instead of kernel cmdline parameter. Will send a
separate patch for this after testing with the changes. Thanks for the
input.
Thanks,
Nikhil V
