Re: why benchmarks need salt

[Luke Mewburn <luke@...>]

On Mon, Jul 20, 2015 at 01:00:47PM -0300, Roberto Ierusalimschy wrote:
  | I was doing some quick-and-dirty benchmarks about 'table.move'. The
  | file 'temp' is here:
  | 
  | --------------------------------------------------------------
  | local a = {}
  | local lim = 10000
  | local rep = 1000
  | for i = 1, lim do a[i] = i end
  | 
  | local t = os.clock()
  | for i = 1, rep do table.move(a, 1, lim, 2) end
  | print(os.clock() - t)
  | --------------------------------------------------------------
  | 
  | Now, see how the times change with the name of the executable:
  | 
  | roberto@arraial:~/prj/lua$ lua temp
  | 0.91
  | roberto@arraial:~/prj/lua$ lua temp
  | 0.91
  | roberto@arraial:~/prj/lua$ mv lua lua1
  | roberto@arraial:~/prj/lua$ lua1 temp
  | 0.57
  | roberto@arraial:~/prj/lua$ lua1 temp
  | 0.57
  | roberto@arraial:~/prj/lua$ mv lua1 sol
  | roberto@arraial:~/prj/lua$ sol temp
  | 0.91
  | roberto@arraial:~/prj/lua$ sol temp
  | 0.91
  | roberto@arraial:~/prj/lua$ mv sol sol1
  | roberto@arraial:~/prj/lua$ sol1 temp
  | 0.57
  | roberto@arraial:~/prj/lua$ sol1 temp
  | 0.58

Do you have different programs called "lua" or "sol" in your PATH
that are getting executed instead of the copy in the current
directory?

Or is this definitely a reproducible problem on your platform when the
argv[0] is any 3 character string?

(I don't have "." in my PATH, even at the end, to avoid issues running
the "wrong" version of a program when cd-ed to arbitrary directories.)

regards,
Luke.

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