[TUHS] [SPAM] Re: If not Linux, then what?

Wed Aug 28 13:25:52 AEST 2019

There are many things to dislike about sockets, but one of them -
irrelevant now, perhaps, but hugely troublesome at the time - was the way
they embedded the specific and peculiar behavior of Ethernet, such as
accepting a connection before you know if it's authorized - into the
networking interface. No other networking hardware worked like Ethernet at
either the electrical or the software level, and yet here we are.

I grump, I grump.

-rob

On Wed, Aug 28, 2019 at 1:22 PM Rob Pike <robpike at gmail.com> wrote:

> I find it hard to believe what you remember Dennis saying. The point of
> dmr's streams was to support networking research in the lab and avoid the
> myriad bugs of the mpx interface by stepping around them completely.
>
> Perhaps it's out of context.
>
> -rob
>
>
> On Wed, Aug 28, 2019 at 9:00 AM Larry McVoy <lm at mcvoy.com> wrote:
>
>> streams were OK but Dennis himself told me he didn't intend them for
>> networking.  They were a simple mechanism for pushing line disciplines
>> onto tty drivers.
>>
>> I can't remember exactly what he said, this was back in ~1988 or so
>> and I was talking to him about the STREAMS stuff.  He wasn't very
>> happy with it and I'm pretty sure he said something like streams
>> weren't design to mux multiple sources or network connections.
>> I think he sort of grudgingly gave credit that they made it work
>> but he seemed to think that it was twisting streams more than they
>> should be twisted.
>>
>> On Wed, Aug 28, 2019 at 08:46:35AM +1000, George Michaelson wrote:
>> > oh maybe I meant "streams" not "STREAMS" I always got confused if the
>> > original ritchie spec was upper or lower case. Charles Forsyth coded
>> > it into the York Uni Vaxen, worked fine. I left shortly after to do
>> > stuff at UCL, it only came back into my life when at UQ in Australia
>> > we got an ICL "certified" SYSV host and along side dead technology
>> > like RFS up it popped (I think ICL had coded an OSI stack we were
>> > testing)
>> >
>> > -G
>> >
>> > On Wed, Aug 28, 2019 at 8:40 AM Larry McVoy <lm at mcvoy.com> wrote:
>> > >
>> > > Wait, are you arguing for STREAMS over sockets?  Dear god, please no.
>> > > Have you ever used STREAMS (not Ritchies streams, those were OK)?
>> > > I have.  I ported Lachman's STREAMS based TCP/IP stack twice, once
>> > > to a long since defunct super computer called the ETA-10 and then
>> > > to SCO Unix.  I've got way more STREAMS experience than most people
>> > > and I can tell you that sockets are WAY WAY better.  I get the "it
>> > > should have just been file I/O" except that I don't.  I tried to
>> > > write a library that let you open up /net/tcp/$host:$port and do
>> > > I/O like it was a file descriptor.  That works for a lot of stuff
>> > > but I ran into problems quickly.  A networking connection is not
>> > > a file handle.  You can make some stuff work but I couldn't figure
>> > > out how to do all of it.   You end up having to do ioctls to handle
>> > > the stuff that doesn't fit well into the file system name space.
>> > > I think plan 9 did this sort of thing, maybe Rob can prove me wrong
>> > > or remember where it didn't match.
>> > >
>> > > I do know that STREAMS came back to Solaris, some VP inked a shitty
>> > > deal with Lachman and bought the rights to the stack.  It was slow
>> > > as molasses in the winter and customers absolutely hated it.  Sun
>> > > got Mentat to redo it for perf but customers still hated it, they
>> > > understood sockets, everyone else had sockets, they wanted sockets
>> > > and they got them.  Sun put them back and nobody ever asked about
>> > > STREAMS again.
>> > >
>> > > On Wed, Aug 28, 2019 at 08:30:01AM +1000, George Michaelson wrote:
>> > > > BSD, but with the original STREAMS semantics, not sockets.
>> > > >
>> > > > DARPA did us no favours accepting sockets in place of simple file
>> I/O
>> > > > semantics for networks.
>> > > >
>> > > > Newcastle connection put the namespace into
>> > > > /.../remote-part/path/to/thing which I felt was also good.
>> > > >
>> > > > So for me, 7 -> BSD -> got worse for some values of worse
>> > > >
>> > > > On Wed, Aug 28, 2019 at 12:56 AM Larry McVoy <lm at mcvoy.com> wrote:
>> > > > >
>> > > > > On Mon, Aug 26, 2019 at 11:14:45PM -0400, Arthur Krewat wrote:
>> > > > > > On 8/26/2019 10:45 PM, Larry McVoy wrote:
>> > > > > > >  Which was that the page cache is
>> > > > > > >*the*  cache.  There is nothing else.
>> > > > > > Yeah, I re-read what you wrote a few times after I replied, and
>> realized
>> > > > > > what you meant ... eventually ;)
>> > > > >
>> > > > > I might be making too big of a deal about it.  mmap semantics
>> mattered
>> > > > > a lot when SMPs first showed up and main memory was small.  It
>> meant
>> > > > > that you could have multiple CPUs seeing and working on the same
>> chunk
>> > > > > of data at the same time.
>> > > > >
>> > > > > It's very similar to way that IOMMUs are exposed to user space
>> these
>> > > > > days, enabling virtual machines direct access to the I/O devices.
>> > > > >
>> > > > > ZFS breaks that model, the data is all in the ARC and if you mmap
>> > > > > it they have to bcopy the data out of the ARC, into the page cache
>> > > > > and now they have a consistency problem, you could modify stuff
>> > > > > via mmap or write and they have to manage that.
>> > > > >
>> > > > > That consistency problem is the main reason that Sun almost
>> completely
>> > > > > killed the buffer cache (it still was used for inodes and
>> directories
>> > > > > but that was it).  That consistency problem is a pain in the rear,
>> > > > > all sorts of race conditions and it tended to bit rot.
>> > > > >
>> > > > > Jeff and Bill are smart people so I suspect they got it right but
>> I'm
>> > > > > still stunned that they took such an architecturally bad approach.
>> > > > > And even more stunned that the oversight people approved it.
>> There
>> > > > > is zero chance that the Sun I worked at would have allowed that.
>> > > > >
>> > > > > --lm
>> > >
>> > > --
>> > > ---
>> > > Larry McVoy                  lm at mcvoy.com
>> http://www.mcvoy.com/lm
>>
>> --
>> ---
>> Larry McVoy                  lm at mcvoy.com
>> http://www.mcvoy.com/lm
>>
>
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