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paketkoll - Check installed distro files for changes (much faster than paccheck) (github.com)

submitted 8 months ago by Vorpal to c/[email protected]

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cross-posted from: https://programming.dev/post/10657765

I made a replacement for the venerable paccheck. It checks if files managed by the package manger have changed and if so reports that back to the user. Unlike paccheck it is cross distro (supports Debian too and could be further extended), and it uses all your CPU cores to be as fast as possible.

Oh and it is written in Rust (that may be a plus or minus depending on your opinion, but it wouldn't have happened at all in any language except Rust, and Rust makes it very easy to add this sort of parallelism).

There are more details (including benchmarks) in the readme on github. Maybe it is useful to some of you.

(The main goal of this project is not actually the program produced so far, but to continue building this into a library. I have a larger project in the planning phase that needs this (in library form) as part of it.)

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[–] [email protected] 2 points 8 months ago (1 children)

Is it faster than running pacman -Qkk packagename?

[–] Vorpal 3 points 8 months ago (1 children)

I have only implemented for checking all packages at the current point in time (as that is what I need later on). It could be possible to add support for checking a single package.

Thank you for reminding me of pacman -Qkk though, I had forgotten it existed.

I just did a test of pacman -Qk and pacman -Qkk (with no package, so checking all of them) and paketkoll is much faster. Based on the man page:

pacman -Qk only checks file exists. I don't have that option, I always check file properties at least, but have the option to skip checking the file hash if the mtime and size matches (paketkoll --trust-mtime). Even though I check more in this scenario I'm still about 4x faster.
pacman -Qkk checks checksum as well (similar to plain paketkoll). It is unclear to me if pacman will check the checksum if the mtime and size matches.

I can report that paketkoll handily beats pacman in both scenarios (pacman -Qk is slower than paketkoll --trust-mtime, and pacman -Qkk is much slower than plain paketkoll). Below are the output of using the hyperfine benchmarking tool:

$ hyperfine -i -N --warmup=1 "paketkoll --trust-mtime" "paketkoll" "pacman -Qk" "pacman -Qkk"
Benchmark 1: paketkoll --trust-mtime
  Time (mean ± σ):     246.4 ms ±   7.5 ms    [User: 1223.3 ms, System: 1247.7 ms]
  Range (min … max):   238.2 ms … 261.7 ms    11 runs
 
  Warning: Ignoring non-zero exit code.
 
Benchmark 2: paketkoll
  Time (mean ± σ):      5.312 s ±  0.387 s    [User: 17.321 s, System: 13.461 s]
  Range (min … max):    4.907 s …  6.058 s    10 runs
 
  Warning: Ignoring non-zero exit code.
 
Benchmark 3: pacman -Qk
  Time (mean ± σ):     976.7 ms ±   5.0 ms    [User: 101.9 ms, System: 873.5 ms]
  Range (min … max):   970.3 ms … 984.6 ms    10 runs
 
Benchmark 4: pacman -Qkk
  Time (mean ± σ):     86.467 s ±  0.160 s    [User: 53.327 s, System: 16.404 s]
  Range (min … max):   86.315 s … 86.819 s    10 runs
 
  Warning: Ignoring non-zero exit code.

It appears that pacman -Qkk is much slower than paccheck --file-properties --sha256sum even. I don't know how that is possible!

The above benchmarks were executed on an AMD Ryzen 5600X with 32 GB RAM and an Gen3 NVME SSD. pacman -Syu executed as of yesterday most recently. Disk cache was hot in between runs for all the tools, that would make the first run a bit slower for all the tools (but not to a large extent on a SSD, I can imagine it would dominate on a mechanical HDD though)

In conclusion:

When checking just file properties paketkoll is 3.96 times faster than pacman checking just if the files exist
When checking checksums paketkoll is 16.3 times faster than pacman checking file properties. This is impressive on a 6 core/12 thread CPU. pacman must be doing something exceedingly stupid here (might be worth looking into, perhaps it is checking both sha256sum and md5sum, which is totally unneeded). Compared to paccheck I see a 7x speedup in that scenario which is more in line with what I would expect.

[–] [email protected] 1 points 8 months ago (1 children)

Damn, that's impressive.

[–] Vorpal 2 points 8 months ago

I went ahead and implemented support for filtering packages (just made a new release: v0.1.3).

I am of course still faster. Here are two examples that show a small package (where it doesn't really matter that much) and a huge package (where it makes a massive difference). Excuse the strange paths, this is straight from the development tree.

Lets check on pacman itself, and lets include config files too (not sure if pacman has that option even?). Config files or not doesn't make a measurable difference though:

$ hyperfine -i -N --warmup 1 "./target/release/paketkoll --config-files=include pacman" "pacman -Qkk pacman"
Benchmark 1: ./target/release/paketkoll --config-files=include pacman
  Time (mean ± σ):      14.0 ms ±   0.2 ms    [User: 21.1 ms, System: 19.0 ms]
  Range (min … max):    13.4 ms …  14.5 ms    216 runs
 
  Warning: Ignoring non-zero exit code.
 
Benchmark 2: pacman -Qkk pacman
  Time (mean ± σ):      20.2 ms ±   0.2 ms    [User: 11.2 ms, System: 8.8 ms]
  Range (min … max):    19.9 ms …  21.1 ms    147 runs
 
Summary
  ./target/release/paketkoll --config-files=include pacman ran
    1.44 ± 0.02 times faster than pacman -Qkk pacman

Lets check on davici-resolve as well. Which is massive (5.89 GB):

$ hyperfine -i -N --warmup 1 "./target/release/paketkoll --config-files=include pacman davinci-resolve" "pacman -Qkk pacman davinci-resolve"
Benchmark 1: ./target/release/paketkoll --config-files=include pacman davinci-resolve
  Time (mean ± σ):     770.8 ms ±   4.3 ms    [User: 2891.2 ms, System: 641.5 ms]
  Range (min … max):   765.8 ms … 778.7 ms    10 runs
 
  Warning: Ignoring non-zero exit code.
 
Benchmark 2: pacman -Qkk pacman davinci-resolve
  Time (mean ± σ):     10.589 s ±  0.018 s    [User: 9.371 s, System: 1.207 s]
  Range (min … max):   10.550 s … 10.620 s    10 runs
 
  Warning: Ignoring non-zero exit code.
 
Summary
  ./target/release/paketkoll --config-files=include pacman davinci-resolve ran
   13.74 ± 0.08 times faster than pacman -Qkk pacman davinci-resolve

What about a some midsized packages (vtk 359 MB, linux 131 MB)?

$ hyperfine -i -N --warmup 1 "./target/release/paketkoll vtk" "pacman -Qkk vtk"
Benchmark 1: ./target/release/paketkoll vtk
  Time (mean ± σ):      46.4 ms ±   0.6 ms    [User: 204.9 ms, System: 93.4 ms]
  Range (min … max):    45.7 ms …  48.8 ms    65 runs
 
Benchmark 2: pacman -Qkk vtk
  Time (mean ± σ):     702.7 ms ±   4.4 ms    [User: 590.0 ms, System: 109.9 ms]
  Range (min … max):   698.6 ms … 710.6 ms    10 runs
 
Summary
  ./target/release/paketkoll vtk ran
   15.15 ± 0.23 times faster than pacman -Qkk vtk

$ hyperfine -i -N --warmup 1 "./target/release/paketkoll linux" "pacman -Qkk linux"
Benchmark 1: ./target/release/paketkoll linux
  Time (mean ± σ):      34.9 ms ±   0.3 ms    [User: 95.0 ms, System: 78.2 ms]
  Range (min … max):    34.2 ms …  36.4 ms    84 runs
 
Benchmark 2: pacman -Qkk linux
  Time (mean ± σ):     313.9 ms ±   0.4 ms    [User: 233.6 ms, System: 79.8 ms]
  Range (min … max):   313.4 ms … 314.5 ms    10 runs
 
Summary
  ./target/release/paketkoll linux ran
    9.00 ± 0.09 times faster than pacman -Qkk linux

For small sizes where neither tool performs much work, the majority is spent on fixed overheads that both tools have (loading the binary, setting up glibc internals, parsing the command line arguments, etc). For medium sizes paketkoll pulls ahead quite rapidly. And for large sizes pacman is painfully slow.

Just for laughs I decided to check an empty meta-package (base, 0 bytes). Here pacman actually beats paketkoll, slightly. Not a useful scenario, but for full transparency I should include it:

$ hyperfine -i -N --warmup 1 "./target/release/paketkoll base" "pacman -Qkk base"
Benchmark 1: ./target/release/paketkoll base
  Time (mean ± σ):      13.3 ms ±   0.2 ms    [User: 15.3 ms, System: 18.8 ms]
  Range (min … max):    12.8 ms …  14.1 ms    218 runs
 
Benchmark 2: pacman -Qkk base
  Time (mean ± σ):       8.8 ms ±   0.2 ms    [User: 2.8 ms, System: 5.8 ms]
  Range (min … max):     8.4 ms …  10.0 ms    327 runs
 
Summary
  pacman -Qkk base ran
    1.52 ± 0.05 times faster than ./target/release/paketkoll base

I always start a threadpool regardless of if I have work to do (and changing that would slow the case I actually care about). That is the most likely cause of this slightly larger fixed overhead.