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

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(a)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(a)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(a)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 >