> asynchronous IO architecture only beaten by Solaris asynchronous IO
Wait, what? Event ports are nice, but they're still inherently limited by the UNIX "readiness"-oriented I/O interface. And they don't provide a unified file/socket asynchronous I/O interface, either. (No UNIX does.)
VMS got I/O right: I/O request packets and a completion-oriented I/O interface. This, combined with multiple IRQ levels, is the key element behind Windows' superior virtual memory management, combined file system cache management and actual asynchronous file I/O.
Strip everything else away from NT and UNIX and it comes down to buffer-based I/O versus packet-based I/O (Irps), APCs instead of signals, and multiple IRQ levels (not just hi/lo).
Side note: AIX copied the NT I/O completion port API verbatim. (Except they ignore the concurrency parameter, which speaks volumes about impedance mismatch between multiple threads and the traditional process-based UNIX IPC model.)
Another tidbit I find interesting: David Cutler was 47 when Bill Gates called him in 1988. He had been working on OS development in a lead capacity since 1975, and subsequently championed the NT kernel that Gates "bet the company on". The core NT APIs that were established in the late 80s and early 90s have stayed the same because they solved the problem correctly the first time 'round.
Linux, on the other hand, was started by Linus in the early nineties (when he was in his 20s) "just for fun". He implemented enough syscalls to get bash to work and went from there. At the end of the day, it was still a UNIX-like operating system.
Cutler knew UNIX inside out and technically knew where and why it was deficient; VMS and thus NT benefited from that.
At the end of the day, it's all about the I/O, and NT has been dominating that since inception.
That is the idea I had from when Solaris introduced asynchronous IO, but I never used them in anger.
I wasn't aware that Aix also had them.
As a side note to that, when we used to develop for Aix, it used the same programming model for shared libraries as Windows does, not what is nowadays common across UNIXes.
So Aix also had import libraries and export symbols descriptions.
Just out of my head:
- pushing C away and allowing C++ on kernel space
- OO ABI besides a procedural one
- object based API even with Win16/32
- asynchronous IO architecture only beaten by Solaris asynchronous IO
- hybrid OS architecture pushing device drivers into user space
- the only shell that can somehow replicate the REPL experience of Xerox PARC systems
- pushing for memory safe systems programming, via C++/CX, .NET Native, static analysis and efforts like GSL at CppCon 2015
- device driver verification via a theorem prover
- integration of container model for mainstream users
- every OS object has security credentials