Add zfs feature flag for arc memory

[jamartin9]

Description

Adds arc support for linux and freebsd.
This is enabled by default with the zfs feature flag but only shown at runtime when arc collection support is detected.

Linux with arc:

Linux no arc:

FreeBSD with arc:

FreeBSD no arc:

Windows no arc:

Issue

This does not include extra arc information like compression ratio.

refs: #688

Testing

If relevant, please state how this was tested. All changes must be tested to work:

If this is a code change, please also indicate which platforms were tested:

I did not test for macOS arc support...(it may work with sysctl like freebsd?)

• Windows
• macOS
• Linux
• FreeBSD

Checklist

If relevant, ensure the following have been met:

• Areas your change affects have been linted using rustfmt (cargo fmt)
• The change has been tested and doesn't appear to cause any unintended breakage
• Documentation has been added/updated if needed (README.md, help menu, etc.)
• The pull request passes the provided CI pipeline
• There are no merge conflicts

Feel free to close the PR if the implementation is too erroneous

[ClementTsang]

Thanks for the PR! Will take a look in a bit. I can test on macOS as well (EDIT: at least to make sure nothing broke, will probably have to look into arc for macos in a separate PR).

[codecov-commenter]

Codecov Report

Merging #784 (92ddbff) into master (658b8c7) will decrease coverage by 0.38%.
The diff coverage is 2.11%.

@@            Coverage Diff             @@
##           master     #784      +/-   ##
==========================================
- Coverage   24.04%   23.66%   -0.39%     
==========================================
  Files          60       60              
  Lines       13008    13239     +231     
==========================================
+ Hits         3128     3133       +5     
- Misses       9880    10106     +226     

Impacted Files	Coverage Δ
src/app/data_harvester.rs	0.00% <0.00%> (ø)
src/app/data_harvester/memory/general/heim.rs	0.00% <0.00%> (ø)
src/bin/main.rs	13.11% <0.00%> (-0.68%)	⬇️
src/canvas.rs	15.94% <0.00%> (-0.37%)	⬇️
src/canvas/widgets/mem_basic.rs	0.00% <0.00%> (ø)
src/canvas/widgets/mem_graph.rs	0.00% <0.00%> (ø)
src/constants.rs	0.00% <0.00%> (ø)
src/data_conversion.rs	12.94% <0.00%> (-1.46%)	⬇️
src/lib.rs	6.85% <0.00%> (-0.09%)	⬇️
src/options.rs	61.24% <ø> (ø)
... and 3 more

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[ClementTsang]

Mostly just some nits. Otherwise looks fine. Will run on macOS and check it off if it seems fine later tomorrow.

[jamartin9]

Mostly just some nits. Otherwise looks fine. Will run on macOS and check it off if it seems fine later tomorrow.

@ClementTsang Thanks for your timely response and great feedback!

I have tried to address the comments raised. If more is needed please let me know.
I gave the code changes a quick cargo clippy and cargo run on the three platforms I have access to again.

Additionally I would like to know if you think this approach would be satisfactory for say Video Card RAM with the gpu feature flag?(I would extract out the initialization into a once_cell or something like the nvml-wrapper docs say of course) I can raise this in the feature request issue 298 if you would rather answer there instead...

EDIT: forgot a feature flag... You may want to squash if you merge.

[ClementTsang]

LGTM. Thanks for the PR!

@all-contributors please add @jamartin9 for code.

[allcontributors]

@ClementTsang

I've put up a pull request to add @jamartin9! 🎉

[ClementTsang]

Additionally I would like to know if you think this approach would be satisfactory for say Video Card RAM with the gpu feature flag?(I would extract out the initialization into a once_cell or something like the nvml-wrapper docs say of course) I can raise this in the feature request issue 298 if you would rather answer there instead...

I think that could work, yeah.

[Lyndeno]

Does zfs expose similar information for L2ARC? If so, maybe that could be shown as well?

[jamartin9]

@Lyndeno Does zfs expose similar information for L2ARC? If so, maybe that could be shown as well?

Yes arcstats has l2 information like l2_size/l2_asize, l2_write_bytes,l2_read_bytes.
The information could be added in the disk widget. ( Like the iostats for zfs zpools in #1248 ; by adding an entry to DiskHarvest and IoHarvest for the device/usage. )
The feature could be added by anyone inclined to do so. I do not use l2 at this moment.