[erlang-patches] DTrace patch, review draft 3, 27 Nov revision

[Scott Lystig Fritchie]

Hej, hi, I've got another draft of the DTrace review patch.  It's still
on the same repo (git://github.com/slfritchie/otp) and same branch
(dtrace-review3).

The old head for the previous version of the dtrace-review patch was
4242b9c0eca65b767eabcc192d980fa3754d5b33.  The new head for that branch
is 2913fb96db4ab35776bd4c11afd82b494f554689.

I hope that I've covered all of the review comments since the last
draft.  The exceptions are related to comments about adding overhead to
the prim_file.erl<->efile_drv.c driver protocol and adding extra
data/vars/struct members of various parts of efile_drv.c: I've done
nothing, pending replies to my replies late last week.

Using "git diff 4242b9c0eca65b767eabcc192d980fa3754d5b33..dtrace-review3"
ought to show what's changed between the last draft and the new forced
push.  I've reviewed each of the 3 email messages & their requested
changes, compared them to the diff, and all seem to be addressed.
(Except for the exceptions noted above.)  I hope the barley beer isn't
interfering too much with the review.  :-)

I'm not 100% certain if I've managed to address all of the
set-but-unused variables that were initially commented up: I made a
single pass after looking at some GCC 4.5 output, adding
ERTS_DECLARE_DUMMY() macros at various places, but I don't know if I
found 100% of the ones that the DTrace code touches.  There are many
more for code that I haven't modified, so I left them alone.

I hope I've fixed all of the Windows problems.  If not, please yell at
me ASAP with the bitter details.

There is one problem that I'm aware of at the moment: on my Solaris 10
box, attempts to use the following when DTrace is enabled:

    ok = dtrace:init().
    dtrace:p(42).

... will cause a core dump.  There's some problem with the linker that I
don't understand yet.  This branch is full of so many changes, and the
code freeze is coming soon, that I'll try to investigate this problem on
Sunday 27 November and see what I can see.

-Scott