From: Dan Cross <crossd@gmail.com>
To: Bakul Shah <bakul@iitbombay.org>
Cc: The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: [TUHS] Re: Clever code (was Re: Re: Stdin Redirect in Cu History/Alternatives?
Date: Thu, 15 Dec 2022 09:02:08 -0500 [thread overview]
Message-ID: <CAEoi9W5gp=2UrKTCfdCG583quk7Ay7j-G0HMxVs8BA-PbrfnFw@mail.gmail.com> (raw)
In-Reply-To: <CD9133DB-DC04-447B-9A7E-19ABDA655251@iitbombay.org>
On Thu, Dec 15, 2022 at 12:38 AM Bakul Shah <bakul@iitbombay.org> wrote:
> Don't see how unless they put multiple related services in the same
> address space, which reduces context switching but tends toward a
> monokernel (& increased coupling). Unless I am misunderstanding you.
I don't see why two services in a microkernel couldn't arrange to
share a region of memory and implement bidirectional queues
between themselves. With an appropriate signalling mechanism,
you'd still be context switching but avoiding a lot of copying.
- Dan C.
> > On Dec 14, 2022, at 6:54 PM, Larry McVoy <lm@mcvoy.com> wrote:
> >
> > Wasn't there some statement that QNX dropped some of these? Copy plus
> > context switch?
> >
> > On Wed, Dec 14, 2022 at 04:29:45PM -0800, Bakul Shah wrote:
> >> On Dec 11, 2022, at 7:09 PM, Andrew Warkentin <andreww591@gmail.com> wrote:
> >>>
> >>> It's not necessarily true that microkernels are significantly slower.
> >>
> >> uKernels are usually quite fast as they do so little. What can be slow
> >> is emulating a Unix like OS on top due to context switches. For instance,
> >> a user process doing read() will have the following context switches:
> >>
> >> userProc->uK->FileSystem->uK->diskDriver->uk->FileSysem->uK->userProc
> >>
> >> or worse (I didn't account for a few things). Because of this even some
> >> uKernels run a few critical services + drivers in the supervisor mode.
> >> But overall slowdown of such a unix emulation will very much depend on the
> >> workload and also what kind of performance improvements you are willing to
> >> try in a complex kernel vs same services running in user mode.
> >>
> >> At present the linux kernel has about 31+ Million lines (accounting for
> >> all architectures, filesystems, device drivers etc.). The FreeBSD 13.x
> >> kernel is about 8.7M LoC (of which 44-45% are in device drivers). I only
> >> counted .c and .h files. In contract FreeBSD 2.2.2 kernel has ~554K LoC.
> >> This LoC growth is entirely understandable but I wonder how things may
> >> have turned out in an alternate universe of uKernel based designs....
> >
> > --
> > ---
> > Larry McVoy Retired to fishing http://www.mcvoy.com/lm/boat
>
next prev parent reply other threads:[~2022-12-15 14:03 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-10 19:38 [TUHS] " segaloco via TUHS
2022-12-11 0:22 ` [TUHS] " Clem Cole
2022-12-11 2:37 ` segaloco via TUHS
2022-12-11 13:59 ` Michael Kjörling
2022-12-11 14:28 ` Steve Nickolas
2022-12-11 15:04 ` Dan Cross
2022-12-13 1:54 ` Larry McVoy
2022-12-11 17:18 ` Adam Thornton
2022-12-11 18:54 ` Michael Kjörling
2022-12-11 19:55 ` Dave Horsfall
2022-12-11 20:03 ` Larry McVoy
2022-12-11 23:22 ` segaloco via TUHS
2022-12-12 2:15 ` [TUHS] Clever code (was " Bakul Shah
2022-12-12 2:44 ` [TUHS] " Steve Nickolas
2022-12-12 3:09 ` Andrew Warkentin
2022-12-12 3:34 ` Larry McVoy
2022-12-12 5:00 ` Kevin Bowling
2022-12-12 5:26 ` Andrew Warkentin
2022-12-12 15:02 ` Larry McVoy
2022-12-12 15:29 ` Clem Cole
2022-12-12 15:39 ` Dan Cross
2022-12-12 16:04 ` Larry McVoy
2022-12-12 16:26 ` Clem Cole
2022-12-12 22:20 ` Liam Proven
2022-12-12 23:10 ` segaloco via TUHS
2022-12-12 23:24 ` Larry McVoy
2022-12-13 2:00 ` Andrew Warkentin
2022-12-13 13:37 ` Larry McVoy
2022-12-13 23:00 ` Andrew Warkentin
2022-12-14 1:05 ` Larry McVoy
2022-12-14 1:40 ` segaloco via TUHS
2022-12-14 6:32 ` Rich Morin
2022-12-14 2:01 ` Andrew Warkentin
2022-12-14 7:49 ` arnold
2022-12-14 11:54 ` Brad Spencer
2022-12-14 12:08 ` [TUHS] Re: (TUHS -> COFF?) Re: Clever code Michael Kjörling
2022-12-14 15:14 ` [TUHS] Microware's OS-9 (was: Clever code) G. Branden Robinson
2022-12-14 22:41 ` [TUHS] " John Cowan
2022-12-14 9:46 ` [TUHS] Re: Clever code (was Re: Re: Stdin Redirect in Cu History/Alternatives? Harald Arnesen
2022-12-15 18:33 ` Liam Proven
2022-12-16 10:42 ` Harald Arnesen
2022-12-18 14:05 ` Liam Proven
2022-12-18 15:08 ` Stuff Received
2022-12-19 11:47 ` Liam Proven
2022-12-20 8:30 ` Andrew Warkentin
2022-12-20 11:57 ` Liam Proven
2022-12-15 0:29 ` Bakul Shah
2022-12-15 2:54 ` Larry McVoy
2022-12-15 5:36 ` Bakul Shah
2022-12-15 14:02 ` Dan Cross [this message]
2022-12-15 14:06 ` Larry McVoy
2022-12-15 14:18 ` Dan Cross
2022-12-15 14:02 ` Larry McVoy
2022-12-15 8:01 ` Andrew Warkentin
2022-12-12 9:48 ` [TUHS] Re: Clever code Michael Kjörling
2022-12-12 21:34 ` [TUHS] Re: Stdin Redirect in Cu History/Alternatives? Dave Horsfall
2022-12-12 21:46 ` Chet Ramey
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