On Mon, Sep 25, 2017 at 9:18 AM, Larry McVoy <lm@mcvoy.com> wrote:

On Mon, Sep 25, 2017 at 10:16:11AM -0400, Clem Cole wrote:
> So what I'm asking us to try to do, is not just look at the technology in a
> vacuum. Why was it not interesting to /proc for BSD. Clearly, Linux
> added it (differently than Eighth Edition of course and the 4.4
> implementation was much more like V8 that Linux would settle). People did
> do the work to use it.

Linux's /proc was hugely different than the AT&T /proc, in a good way in
my opinion. It's sort of Tcl like :-), everything is a string. So you
can look at the files with cat. I think plan 9 went this way as well.

I both love and hate this setup...

And the Linux /proc did and does so much more than AT&T /proc.

Which is the other issue with the inherited 4.4 /proc

[...]

> So why did *BSD not bring those versions of the utilities back?
>
> My >>guess<< while they had added some things (like /proc) it was different
> again and we got into the BSD != Linux stuff - which has been the UNIX war
> all over again.

Yeah, I don't see the two being compat. They could overlap but when you get
into specific tuning variables they won't match.

There was very little overlap. And much of what was exported in linux as /proc/blah was available as a syctl which mean the pressure to expand /proc was lessened. There's pros and cons to sysctl (which is basically a second name space for data from/about the kernel), but it was the path taken. Filesystems can go too far (cf the fiasco of the efivar filesystem where you could brick your box with an rm -rf, oops), and they can also be taken not far enough. There's good reasons to avoid filesystems that are intrusive into every part of the system (sysctl has a more restricted context to execute in which can be more helpful than trying to cope with vnodes and such in every driver). There's also bad reasons to avoid filesystems as well (say because your VFS abstraction layer is complicated and difficult to use)...

I suspect that no /proc in BSD is simple, there wasn't anyone who wanted to
put in the time to evolve it and maintain it.

That's it in a one line summary. I posted a few more details as well, but that's basically it. When the time came, nobody cared enough to even object... Certainly nobody cared enough to understand the complex interactions with other subsystems as they evolved to keep it up to snuff, let alone innovate with new things to keep it interesting.

Warner