8 ms·

> Elixir would be more energy efficient than bash as far as I can tell For long running scripts perhaps. BEAM idles at ~50Mb, and startup is often more than 50

> Elixir would be more energy efficient than bash as far as I can tell For long running scripts perhaps. BEAM idles at ~50Mb, and startup is often more than 500ms. Eg: $ time ./hello hello world real 0m0,009s user 0m0,003s sys 0m0,007s $ time elixir hello.exs hello world real 0m0,755s user 0m0,992s sys 0m0,304s Where the first example is a BASH script.

throwawaymaths 3y ago
Yes because when you load elixir you're loading the entire gOddamn Erlang VM. Which you might want for things like reliable parallel downloading, but you don't for hello world.
toast0 3y ago
I don't know that you'll get it down to 10 ms, but you can get beam startup a lot faster if you adjust parameters. The default startup does a lot of things you simply don't need in most shell scripts. Starting a bunch of threads, setting up dist, I can't remember what else off the top of my head.
- fredrikholm 3y ago
  Even without the shell and with epmd turned off we're still in the ball bark of 200-300ms: $ time erl -eval 'io:format("~s~n", [os:cmd("echo hello world")]), halt(0, [{flush, false}]).' -noshell -start_epmd false hello world real 0m0,332s user 0m0,461s sys 0m0,092s I spent some time last year trying to get those numbers down but this is as far as I made it. Do you know of any more flags that might help?
  - toast0 3y ago
    Try -boot no_dot_erlang A couple years ago that got me to 100 ms https://news.ycombinator.com/item?id=25243246 https://news.ycombinator.com/item?id=25243246 Today's measurements with FreeBSD 13.2 on the same Pentium G3470 time /bin/sh -c "echo hi" hi real 0m0.004s user 0m0.001s sys 0m0.002s time /usr/local/bin/bash -c "echo hi" hi hi real 0m0.006s user 0m0.007s sys 0m0.000s time /usr/local/lib/erlang26/bin/erl -eval 'io:format("hi~n"), halt(0, [{flush, false}])' Erlang/OTP 26 [erts-14.2.1] [source] [64-bit] [smp:2:2] [ds:2:2:10] [async-threads:1] [jit:ns] [dtrace] [sharing-preserving] hi real 0m0.197s user 0m0.178s sys 0m0.018s time /usr/local/lib/erlang26/bin/erl -eval 'io:format("hi~n"), halt(0, [{flush, false}])' -noshell -start_epmd false -boot no_dot_erlang hi real 0m0.183s user 0m0.181s sys 0m0.011s This doesn't look very good, actually! FreeBSD has OTP 21-26 available through pkg, I ran the same thing on each of them several times to warm up, and get (real time): 21: 81ms 22: 81ms 23: 74ms 24: 129ms 25: 135ms 26: 177ms So maybe there's some new stuff that needs to be avoided now.
    - fredrikholm 3y ago
      It was your original post that set me on course for experimenting with startup times, cheers! Unfortunately, that final flag doesn't change much on 26 for me. IIRC I dropped a bunch of flags after concluding that no shell and no epmd were the only flags that I noticed improvements with.
      - toast0 3y ago
        Yeah, it looks like it got a lot worse. I don't think it's JIT, because I ran a test with a 32-bit version of OTP 26 (JIT is only available for 64-bit x86 and arm). But I'm not sure what it is. Send me an email (in profile), and I'll try to find some time to look closer.

throwawaymaths 3y ago

Yes because when you load elixir you're loading the entire gOddamn Erlang VM. Which you might want for things like reliable parallel downloading, but you don't for hello world.

toast0 3y ago

I don't know that you'll get it down to 10 ms, but you can get beam startup a lot faster if you adjust parameters. The default startup does a lot of things you simply don't need in most shell scripts. Starting a bunch of threads, setting up dist, I can't remember what else off the top of my head.

fredrikholm 3y ago
Even without the shell and with epmd turned off we're still in the ball bark of 200-300ms: $ time erl -eval 'io:format("~s~n", [os:cmd("echo hello world")]), halt(0, [{flush, false}]).' -noshell -start_epmd false hello world real 0m0,332s user 0m0,461s sys 0m0,092s I spent some time last year trying to get those numbers down but this is as far as I made it. Do you know of any more flags that might help?
- toast0 3y ago
  Try -boot no_dot_erlang A couple years ago that got me to 100 ms https://news.ycombinator.com/item?id=25243246 https://news.ycombinator.com/item?id=25243246 Today's measurements with FreeBSD 13.2 on the same Pentium G3470 time /bin/sh -c "echo hi" hi real 0m0.004s user 0m0.001s sys 0m0.002s time /usr/local/bin/bash -c "echo hi" hi hi real 0m0.006s user 0m0.007s sys 0m0.000s time /usr/local/lib/erlang26/bin/erl -eval 'io:format("hi~n"), halt(0, [{flush, false}])' Erlang/OTP 26 [erts-14.2.1] [source] [64-bit] [smp:2:2] [ds:2:2:10] [async-threads:1] [jit:ns] [dtrace] [sharing-preserving] hi real 0m0.197s user 0m0.178s sys 0m0.018s time /usr/local/lib/erlang26/bin/erl -eval 'io:format("hi~n"), halt(0, [{flush, false}])' -noshell -start_epmd false -boot no_dot_erlang hi real 0m0.183s user 0m0.181s sys 0m0.011s This doesn't look very good, actually! FreeBSD has OTP 21-26 available through pkg, I ran the same thing on each of them several times to warm up, and get (real time): 21: 81ms 22: 81ms 23: 74ms 24: 129ms 25: 135ms 26: 177ms So maybe there's some new stuff that needs to be avoided now.
  - fredrikholm 3y ago
    It was your original post that set me on course for experimenting with startup times, cheers! Unfortunately, that final flag doesn't change much on 26 for me. IIRC I dropped a bunch of flags after concluding that no shell and no epmd were the only flags that I noticed improvements with.
    - toast0 3y ago
      Yeah, it looks like it got a lot worse. I don't think it's JIT, because I ran a test with a 32-bit version of OTP 26 (JIT is only available for 64-bit x86 and arm). But I'm not sure what it is. Send me an email (in profile), and I'll try to find some time to look closer.