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From: jnc@mercury.lcs.mit.edu (Noel Chiappa)
To: tuhs@minnie.tuhs.org
Cc: jnc@mercury.lcs.mit.edu
Subject: Re: [TUHS] CMU Mach sources?
Date: Sun, 23 Jun 2019 18:08:56 -0400 (EDT)	[thread overview]
Message-ID: <20190623220856.AADD018C0CF@mercury.lcs.mit.edu> (raw)

    > From: Andrew Warkentin

    > Mach and the other kernels influenced by it basically destroyed the
    > reputation of microkernels ...  a simple read() of a disk file, which is
    > a single kernel call on a monolithic kernel and usually two context
    > switches on QNX, takes at least 8 context switches - client->VFS->disk
    > FS->partition driver->disk driver and back again).

Hammer-nail syndrome.

When the only tool you have for creating separate subsystems is processes, you
wind up with a lot of processes. Who'd a thunk it.

A system with a segmented memory which allows subroutine calls from one subsystem
to another will have a lot less overhead. It does take hardware support to be
really efficient, though. The x86 processors had that support, until Intel dropped
it from the latest ones because nobody used it.

Excuse me while I go bang my head on a very hard wall until the pain stops.

       Noel


             reply	other threads:[~2019-06-23 22:09 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-23 22:08 Noel Chiappa [this message]
2019-06-23 23:54 ` Theodore Ts'o
2019-06-24 17:04   ` Jason Stevens
  -- strict thread matches above, loose matches on Subject: below --
2019-07-01 13:20 Jason Stevens
2019-06-23  4:38 Chris Hanson
2019-06-23  5:15 ` Larry McVoy
2019-06-23  8:52   ` Andrew Warkentin
2019-06-23 13:39   ` Jon Forrest
2019-06-23 13:59     ` arnold
2019-06-23 14:03     ` Jason Stevens
2019-06-23  8:04 ` Jason Stevens
2019-06-23 14:54   ` Henry Bent
2019-06-23 21:52     ` Clem Cole
2019-06-25  0:06       ` Larry McVoy
2019-06-25  0:31         ` Theodore Ts'o
2019-06-25  0:45           ` Larry McVoy
2019-06-25  0:55             ` Kurt H Maier
2019-06-25  4:18               ` Larry McVoy
2019-06-25  1:00             ` Richard Salz
2019-06-25  8:00               ` Kevin Bowling
2019-06-25 12:11                 ` Arthur Krewat
2019-06-25 12:17                   ` Arthur Krewat
2019-06-26  2:45               ` Kurt H Maier
2019-06-26  2:56                 ` Larry McVoy
2019-06-26 15:11                   ` Theodore Ts'o
2019-06-26 17:44                     ` Larry McVoy
2019-06-26 18:01                       ` arnold
2019-06-26 18:18                         ` Warner Losh
2019-06-26 19:22                       ` Chris Hanson
2019-06-26 19:32                         ` Ben Greenfield via TUHS
2019-06-26 20:21                           ` Larry McVoy
2019-06-27  0:22                             ` Chris Hanson
2019-06-27  1:02                               ` Larry McVoy
2019-06-27  1:26                                 ` Chris Hanson
2019-06-27  4:01                             ` Lyndon Nerenberg
2019-06-27 10:34                               ` Ben Greenfield via TUHS
2019-06-27 10:59                                 ` arnold
2019-06-27 11:13                                   ` Ben Greenfield via TUHS
2019-06-27 11:39                                     ` arnold
2019-06-27 14:58                                     ` Warner Losh
2019-06-27 17:25                                       ` Larry McVoy
2019-06-26 19:30                       ` Dennis Boone
2019-06-26 19:25                     ` Adam Thornton
2019-06-23  8:27 ` Kevin Bowling
2019-06-25  3:07 ` Gregg Levine
2019-06-25  8:15   ` Kevin Bowling
2019-06-25 18:18   ` Chris Hanson
2019-06-25 20:23     ` Gregg Levine
2019-06-26  1:04       ` Jason Stevens
2019-06-26  0:53     ` Jason Stevens
2019-06-25  7:49 ` Jason Stevens
2019-06-25  7:59   ` Andreas Grapentin

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