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Comment by exacube | Hacker News Reader

Author makes a comment that "If we just run /bin/true, we can do 500 of them in a second" -- this is very platform dependent -- i think Linux' process creation is supposed to be 1-2 orders of magnitude faster than Windows, for example (i don't have the exact numbers though).

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The implementation of true also makes a difference! Not quite an order of magnitude difference, though (except for the shell builtin).

    method           Hz comment
    --------------------------------------------------------
    empty file      500 an empty file gets passed to /bin/sh
    dynamic libc   1000 "int main { return 0; }" -> gcc
    static libc    1500 the same, but with "gcc -static"
    assembly       2000 see below
    bash builtin 150000 avoids hitting the kernel or filesystem

The empty file is the "traditional" implementation of true on Unix.

The assembly solution was my attempt at doing the littlest amount possible, because libc initialization still takes time:

    .globl _start
    _start:
    	movl $1, %eax 		# %eax = SYS_exit
    	xorl %ebx, %ebx		# %ebx = 0 (exit status)
    	int $0x80

This depends in part on how big the process that's forking is. http://canonical.org/~kragen/sw/dev3/server.s manages to get quite a bit more than 2000 forks per second out of Linux, which might be in part because it only has two to four virtual memory pages mapped. (see http://canonical.org/~kragen/sw/dev3/httpdito-readme for more details.)

Processes and files on Windows are heavyweight. I recall once speeding up a script by about 100 times by changing something of the form

    a >>$LOG
    b >>$LOG
    ⋮
    c >>$LOG

    {
      a
      b
      ⋮
      c
    } >>$LOG

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