Vorpal

Yes, Sweden really screwed up the first attempt at switching to Gregorian calendar. But there were also multiple countries who switched back and forth a couple of times. Or Switzerland where each administrative region switched separately.

But I think we in Sweden still "win" for worst screw up. Also, there is no good way to handle these dates without specific reference to precise location and which calender they refer to (timestamps will be ambiguous when switching back to Julian calendar).

I would go with the Arch specific https://aur.archlinux.org/packages/aconfmgr-git instead of ansible, since it can save current system state as well. I use it and love it. See another reply on this post for a slightly deeper discussion on it.

I can second this, I use aconfmgr and love it. Especially useful to manage multiple computers (desktop, laptop, old computer doing other things etc).

Though I'm currently planning to rewrite it since it doesn't seem maintained any more, and I want a multi-distro solution (because I also want to use it on my Pis where I run Raspbians). The rewrite will be in Rust, and I'm currently deciding on what configuration language to use. I'm leaning towards rhai (because it seems easy to integrate from the rust side, and I'm not getting too angry at the language when reading the docs for it). Oh and one component for it is already written and published: https://github.com/VorpalBlade/paketkoll is a fast rust replacement for paccheck (that is used internally by aconfmgr to find files that differ).

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.

My guess is that the relevant keyword for the choice of OpenSSL is FIPS. Rusttls doesn't (or at least didn't) have that certification, which matters if you are dealing with US government (directly or indirectly). I believe there is an alternative backend (instead of ring) these days that does have FIPS though.

It very much is (as I even acknowledge at the end of the github README). 😀

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.

Another aspect is that calling a cli command is way slower than a library function (in general). This is most apparent on short running commands, since the overhead is mostly fixed per command invocation rather than scaling with the amount of work or data.

As such I would at the very least keep those commands out of any hot/fast paths.

That assembly program the author compares to is waay bloated. This guy managed with 105 bytes: https://nathanotterness.com/2021/10/tiny_elf_modernized.html (that is with overlapping part of the code into the ELF header and other similar level shenanigans). ;)

All kidding aside, interesting article.

The example FileDescriptorPollContext doesn't really work. What if my runtime uses io-uring instead of polling? Those need very different interfaces to be sound. How do you abstract over that.

Swedish layout. Not ideal for coding (too many things like curly and square brackets etc are under altgr. And tilde and backtick are on dead keys.

But switching back and forth as soon as you need to write Swedish (for the letters åäö) is just too much work. And yes, in the Swedish alphabet they are separate letters, not aao with diacretics.

Two tips that work for me:

• After cargo add I have to sometimes run the "restart rust-analyzer" command from the vscode command pallette (exact wording may be off, I'm on my phone as of writing this comment). Much faster than cargo build.
• Consider using sccache to speed up rebuilds. It helps a lot, though uses a bit of disk space. But disk space is cheap nowadays (as long as you aren't stuck with a laptop with soldered SSD, in which case you know what not to buy next time).