4 ms·

Windows NT had overlapped IO decades before Linux. The Microsoft kernel team were alright.

by inigyou 4mo ago

jchw 4mo ago
Windows NT had many things decades before Linux, I've gotten used to it. There are things Windows has that I still sort of wish Linux had, I mentioned one of them just last night (RDP fast user switching/session roaming.) If we're just strictly talking about low level things, another good one would be synchronization primitives, which I guess we now have some of in Linux verbatim at this point, if only for the sake of emulation. (And of course futex2.)
- inigyou 4mo ago
  I don't think the kernel prohibits fast user switching but you'd have to implement it at the desktop layer too. Think of ctrl-alt-f7, f8 etc. This still works today, you can run X servers as different users on different VT numbers and switch between them. All that's missing is better UI.
  - jchw 4mo ago
    The kernel definitely doesn't, although the VT layer kind of sucks and probably should've never been used to multiplex graphical sessions. (I mean, I get why it was, but oh well.) I was talking about this: https://news.ycombinator.com/item?id=49093002 https://news.ycombinator.com/item?id=49093002 And it winds up being mostly a thing you have to implement in the compositor, but none of them do so far to my knowledge. And of course the same issue applies if you wanted multiple physical seats juggling sessions between them.
    - inigyou 4mo ago
      That's systemd limitations. Who even uses systemd?
      - jchw 4mo ago
        > That's systemd limitations. It's kind of the opposite, systemd-logind provides better seat management than without. I attempted to implement the same concept using libseat and seatd unsuccessfully though I do not remember exactly what I got caught on. (not in kwin but a toy compositor; I have been at this problem for a little while now.) That said, most desktop systems have only implemented systemd-logind in a limited way so far that basically just does what the VT system + display manager was already doing, that's what would need to be worked on in order to make this a reality. I was able to accomplish a prototype with only patches to Kwin, kfreerdp and plasma-login-manager, no need to patch systemd-logind or anything like that. > Who even uses systemd? Well for one thing, almost all of the major distributions; Ubuntu, Debian, Fedora/RHEL, Arch Linux, NixOS, openSuSE? and of course SteamOS now. The only major non-systemd Linux distributions I can think of are Alpine Linux and Gentoo. And Android if you wanted to count that, but I think it is special enough to be considered its own OS that just is Linux-based.
        inigyou 4mo ago
        Then it's libseat and seatd limitations. Why rely on a system that doesn't do what you want? Bypass it and DIY what you actually want.
        jchw 4mo ago
        I personally use a systemd-based distro (NixOS) and logind is able to handle this use case. The point of trying to support libseat was for the sake of non-systemd distros. (Though elogind would probably work too.) I certainly wouldn't DIY this; nothing would support my DIY version, which would defeat the purpose.
        inigyou 4mo ago
        The Linux platform gives you full control. If the box you seek doesn't exist, you have to create your own box instead of thinking inside someone else's box that doesn't even do what you need.
- celiacFun 4mo ago
  Windows strengths: IRPs and fantastic async I/O, ETW events, tooling- windbg xperf driver verifier time travel debugging, RDP, doesn’t claim everything acts like a file Linux strengths: file system, open source ecosystem, ssh, lockless algorithm support
adrian_b 4mo ago
Mechanisms equivalent with the overlapped I/O of Windows NT (1993) already existed 30 years earlier, e.g. in IBM OS/360 and PL/I (1964/1965). The main features that were better in Windows NT than in the UNIX-derived operating systems were inherited from the DEC VAX/VMS operating system (1978) (e.g. WaitForMultipleObjects) and a part of them had been inherited from the even earlier operating system DEC RSX-11M (1974-11) (Dave Cutler also had a major role in those operating systems, so there is nothing surprising about this; Microsoft had to pay a big compensation to DEC, on the order of $ 100M, for the features that were obviously taken from the DEC operating systems). UNIX was very simplified in comparison with the operating systems that were used on bigger computers, and for some things its derivatives never caught up with those older systems, except after 2000. Only "futex" (2002) and "io_uring" (2019) have advanced the state of the art clearly beyond what already existed for AIO on the IBM mainframes around 1964/1966.
- jchw 4mo ago
  To be fair, I think that was the entire challenge in the first place: the contemporary microcomputers were relatively limited on what they could do, so you couldn't necessarily afford to just do everything mainframes were doing. More importantly, it's not clear you would've wanted to. Having the taste and good sense to know what to "steal" and how to "steal" it was already hard enough work. A lot of good ideas took a while to come over, but a lot of probably bad ideas also never did. It's an evergreen interesting fact that Dave Cutler took perhaps a bit too much inspiration from prior VMS work to NT, but I also think there's no need to put an asterisk on it anymore than there is UNIX or anything else; it does ultimately stand on its own. Like great artists, great software architects steal.
- pjmlp 4mo ago
  Including the use of systems programming languages with bounds checking, PL/I, PL.8, PL/S, NEWP, ...
- celiacFun 4mo ago
  I’m not sure you can call anything in Linux/Unix as equivalent to overlapped I/O in Windows given that there aren’t any IRPs

Windows NT had overlapped IO decades before Linux. The Microsoft kernel team were alright.

by inigyou 4mo ago

Windows NT had overlapped IO decades before Linux. The Microsoft kernel team were alright.

jchw 4mo ago

Windows NT had many things decades before Linux, I've gotten used to it. There are things Windows has that I still sort of wish Linux had, I mentioned one of them just last night (RDP fast user switching/session roaming.) If we're just strictly talking about low level things, another good one would be synchronization primitives, which I guess we now have some of in Linux verbatim at this point, if only for the sake of emulation. (And of course futex2.)

inigyou 4mo ago
I don't think the kernel prohibits fast user switching but you'd have to implement it at the desktop layer too. Think of ctrl-alt-f7, f8 etc. This still works today, you can run X servers as different users on different VT numbers and switch between them. All that's missing is better UI.
- jchw 4mo ago
  The kernel definitely doesn't, although the VT layer kind of sucks and probably should've never been used to multiplex graphical sessions. (I mean, I get why it was, but oh well.) I was talking about this: https://news.ycombinator.com/item?id=49093002 https://news.ycombinator.com/item?id=49093002 And it winds up being mostly a thing you have to implement in the compositor, but none of them do so far to my knowledge. And of course the same issue applies if you wanted multiple physical seats juggling sessions between them.
  - inigyou 4mo ago
    That's systemd limitations. Who even uses systemd?
    - jchw 4mo ago
      > That's systemd limitations. It's kind of the opposite, systemd-logind provides better seat management than without. I attempted to implement the same concept using libseat and seatd unsuccessfully though I do not remember exactly what I got caught on. (not in kwin but a toy compositor; I have been at this problem for a little while now.) That said, most desktop systems have only implemented systemd-logind in a limited way so far that basically just does what the VT system + display manager was already doing, that's what would need to be worked on in order to make this a reality. I was able to accomplish a prototype with only patches to Kwin, kfreerdp and plasma-login-manager, no need to patch systemd-logind or anything like that. > Who even uses systemd? Well for one thing, almost all of the major distributions; Ubuntu, Debian, Fedora/RHEL, Arch Linux, NixOS, openSuSE? and of course SteamOS now. The only major non-systemd Linux distributions I can think of are Alpine Linux and Gentoo. And Android if you wanted to count that, but I think it is special enough to be considered its own OS that just is Linux-based.
      - inigyou 4mo ago
        Then it's libseat and seatd limitations. Why rely on a system that doesn't do what you want? Bypass it and DIY what you actually want.
        jchw 4mo ago
        I personally use a systemd-based distro (NixOS) and logind is able to handle this use case. The point of trying to support libseat was for the sake of non-systemd distros. (Though elogind would probably work too.) I certainly wouldn't DIY this; nothing would support my DIY version, which would defeat the purpose.
        inigyou 4mo ago
        The Linux platform gives you full control. If the box you seek doesn't exist, you have to create your own box instead of thinking inside someone else's box that doesn't even do what you need.
celiacFun 4mo ago
Windows strengths: IRPs and fantastic async I/O, ETW events, tooling- windbg xperf driver verifier time travel debugging, RDP, doesn’t claim everything acts like a file Linux strengths: file system, open source ecosystem, ssh, lockless algorithm support

adrian_b 4mo ago

Mechanisms equivalent with the overlapped I/O of Windows NT (1993) already existed 30 years earlier, e.g. in IBM OS/360 and PL/I (1964/1965). The main features that were better in Windows NT than in the UNIX-derived operating systems were inherited from the DEC VAX/VMS operating system (1978) (e.g. WaitForMultipleObjects) and a part of them had been inherited from the even earlier operating system DEC RSX-11M (1974-11) (Dave Cutler also had a major role in those operating systems, so there is nothing surprising about this; Microsoft had to pay a big compensation to DEC, on the order of $ 100M, for the features that were obviously taken from the DEC operating systems). UNIX was very simplified in comparison with the operating systems that were used on bigger computers, and for some things its derivatives never caught up with those older systems, except after 2000. Only "futex" (2002) and "io_uring" (2019) have advanced the state of the art clearly beyond what already existed for AIO on the IBM mainframes around 1964/1966.

jchw 4mo ago
To be fair, I think that was the entire challenge in the first place: the contemporary microcomputers were relatively limited on what they could do, so you couldn't necessarily afford to just do everything mainframes were doing. More importantly, it's not clear you would've wanted to. Having the taste and good sense to know what to "steal" and how to "steal" it was already hard enough work. A lot of good ideas took a while to come over, but a lot of probably bad ideas also never did. It's an evergreen interesting fact that Dave Cutler took perhaps a bit too much inspiration from prior VMS work to NT, but I also think there's no need to put an asterisk on it anymore than there is UNIX or anything else; it does ultimately stand on its own. Like great artists, great software architects steal.
pjmlp 4mo ago
Including the use of systems programming languages with bounds checking, PL/I, PL.8, PL/S, NEWP, ...
celiacFun 4mo ago
I’m not sure you can call anything in Linux/Unix as equivalent to overlapped I/O in Windows given that there aren’t any IRPs