Re: document -j

[Paul D. Smith]

%% Dan Jacobson <address@hidden> writes:

  dj>    Parallel Execution
  dj>    GNU `make' knows how to execute several commands at once.  Normally,
  dj>    `make' will execute only one command at a time, waiting for it to
  dj>    finish before executing the next.  However, the `-j' or
  dj>    `--jobs' option tells `make' to execute many commands simultaneously.

  dj> Well, without examples in the manual, we are left to guess and
  dj> experiment.

The manual is not using the correct terminology here, you're right.  It
should read like this:

   GNU `make' knows how to build several targets at once.  Normally,
   `make' will build only one target at a time, waiting for it to
   finish before building the next.  However, the `-j' or
   `--jobs' option tells `make' to build many targets simultaneously.

  dj> Maybe mention that this shows equivalence with sleep tests:
  dj> $ f=$SECONDS;make -j x y;expr $SECONDS - $f
  dj> $ f=$SECONDS;make x& make y& wait;expr $SECONDS - $f
  dj> But wait, that is only if x and y don't have any dependencies.

I fail to see how this is in any way enlightening.

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