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Message-ID: <CAJZ5v0gaaTj+_LNCyX-Ugw+gNea7QKwrG59ZjbSZcHMvgXp3Hg@mail.gmail.com> Date: Mon, 22 Jan 2024 13:16:22 +0100 From: "Rafael J. Wysocki" <rafael@...nel.org> To: Nikhil V <quic_nprakash@...cinc.com> Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>, Jonathan Corbet <corbet@....net>, Randy Dunlap <rdunlap@...radead.org>, Peter Zijlstra <peterz@...radead.org>, "Steven Rostedt (Google)" <rostedt@...dmis.org>, Tejun Heo <tj@...nel.org>, "Paul E. McKenney" <paulmck@...nel.org>, Catalin Marinas <catalin.marinas@....com>, linux-pm@...r.kernel.org, linux-doc@...r.kernel.org, linux-kernel@...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 RESEND v2 0/4] PM: hibernate: LZ4 compression support On Mon, Jan 22, 2024 at 1:14 PM Nikhil V <quic_nprakash@...cinc.com> 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@...cinc.com> 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@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/@...el/@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!
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