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From: DrPi <314@drpi.fr>
Subject: Re: is there a version of unix written in Ada
Date: Thu, 1 Oct 2020 21:02:17 +0200	[thread overview]
Message-ID: <5f7627bd$0$5863$426a74cc@news.free.fr> (raw)
In-Reply-To: <87o8lml1md.fsf@nightsong.com>

Le 01/10/2020 à 11:46, Paul Rubin a écrit :
> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
>>> You have that either way.
>> That is the point.
> 
> With a conventional OS you have those synchronization delays AND
> you have address translation delays.  With Singularity you still
> have the first, but you get rid of the second.
Address translation is also a security feature. One process can't access 
data of another process. What about this with Singularity ?

> 
>> So, where is performance gain? You still need storing/restoring
>> registers and other context's data upon preemting.
> 
> You run millions of instructions between preemptions, but you take the
> address translation delay on EVERY memory access.
TLB tables are reloaded when switching from one process to another. If 
the switched in process is swapped on disk, then you get a big 
performance hit.
I don't get the point on translation delay on every memory access since 
the address translation is done by efficient specialized hardware.

> 
>> Are you going to recompile and re-link everything in
>> absolute addresses every time anything changes and then reboot?
> 
> Position independent code is a thing.
> 
>> Neither can do anything about it. You either have abstraction, like
>> flat contiguous address space, however implemented, or you do not. The
>> penalty is always there. You can have some relief from the hardware or
>> none.
> 
> Shrug, maybe there is some kind of block allocator like in the old days.
> The original purpose of virtual memory was to allow simulating big ram
> by paging to disk.  Nobody cares about that any more.
Really ?
Have you had a look at Ressource manager, memory tab in Windows 10 ?
You might be surprised. Even when everything fits in physical RAM, there 
are parts of (not used) allocated memory stored on disk. This way 
launching a new process is faster.
At work, I use programs that require big amounts of RAM. Without disk 
swapping, I could not run them (16GB of physical RAM on the machine).
We still do care virtual memory.

> 
> That said, I don't know much about Singularity (never used it, haven't
> read the papers) so maybe I'm missing something important.  But the guys
> who told me about it were knowledgeable and they were impressed by it.
> 
> Anyway, this tangent started from the claim that nothing different had
> been done in OS's in a while.  I don't claim Singularity is great, only
> that it's different.
> 

  parent reply	other threads:[~2020-10-01 19:02 UTC|newest]

Thread overview: 105+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <e3c51e65-b71e-4623-bd58-c94cdbcc3ba6o@googlegroups.com>
2020-07-25  7:37 ` is there a version of unix written in Ada mockturtle
2020-07-26 19:45   ` Stéphane Rivière
2020-07-26 22:15     ` Jeffrey R. Carter
2020-07-27  7:40       ` Stéphane Rivière
2020-07-28 13:08       ` DrPi
2020-07-28 16:48         ` Simon Wright
2020-07-28 17:00           ` Fabien Chouteau
2020-07-29  9:21             ` DrPi
2020-07-29  9:28               ` Fabien Chouteau
2020-07-29 15:02                 ` DrPi
2020-07-29 15:11                   ` Fabien Chouteau
2020-07-29 20:41                     ` DrPi
2020-07-29  9:20           ` DrPi
2020-07-29 16:53             ` Simon Wright
2020-07-29 20:42               ` DrPi
2020-07-25  8:47 ` Niklas Holsti
2020-07-25  9:36   ` Stéphane Rivière
2020-07-25 10:41 ` Luke A. Guest
2020-07-25 14:43 ` Jesper Quorning
2020-07-25 19:20 ` Andreas ZEURCHER
2020-07-27  7:40   ` Stéphane Rivière
2020-07-27 15:00     ` nobody in particular
2020-07-27 14:58   ` nobody in particular
2020-07-27 20:28 ` Shark8
2020-07-30  0:57 ` gdotone
2020-07-31 14:01   ` Shark8
2020-09-23 17:39   ` Olivier Henley
2020-09-25 15:06     ` DrPi
2020-09-25 17:31       ` Andreas ZEURCHER
2020-09-26  8:50         ` DrPi
2020-09-27 18:55           ` Luke A. Guest
2020-09-27 19:07             ` Luke A. Guest
2020-09-27 18:53         ` Luke A. Guest
2020-09-27 14:25     ` Shark8
2020-09-27 15:01       ` Dmitry A. Kazakov
2020-09-27 20:59         ` DrPi
2020-09-28  7:41           ` Dmitry A. Kazakov
2020-09-28 13:48             ` Olivier Henley
2020-09-28 14:48               ` Dmitry A. Kazakov
2020-09-28 16:28                 ` Olivier Henley
2020-09-28 20:30                   ` Dmitry A. Kazakov
2020-09-28 21:06                     ` Shark8
2020-09-28 17:47                 ` Paul Rubin
2020-09-28 20:27                   ` Dmitry A. Kazakov
2020-09-29 23:54                     ` Paul Rubin
2020-09-30  8:18                       ` Dmitry A. Kazakov
2020-09-30 17:27                         ` Paul Rubin
2020-09-30 19:42                           ` Dmitry A. Kazakov
2020-09-30 20:33                             ` Paul Rubin
2020-09-30 21:03                               ` Dmitry A. Kazakov
2020-09-30 22:42                                 ` Randy Brukardt
2020-10-01  9:28                                   ` Dmitry A. Kazakov
2020-10-01  9:59                                     ` J-P. Rosen
2020-10-01 10:21                                       ` Dmitry A. Kazakov
2020-10-01 11:38                                         ` Niklas Holsti
2020-10-01 11:52                                           ` Niklas Holsti
2020-10-01 12:51                                           ` Dmitry A. Kazakov
2020-10-01 14:18                                             ` J-P. Rosen
2020-10-01 15:44                                               ` Dmitry A. Kazakov
2020-10-01 22:10                                                 ` Randy Brukardt
2020-10-02  5:36                                                 ` J-P. Rosen
2020-10-02  6:56                                                   ` Dmitry A. Kazakov
2020-10-02  7:42                                                     ` J-P. Rosen
2020-10-03  3:14                                                       ` Randy Brukardt
2020-10-01 15:38                                             ` Niklas Holsti
2020-10-01 16:06                                               ` Dmitry A. Kazakov
2020-10-01 17:01                                                 ` Niklas Holsti
2020-10-01 17:37                                                   ` Dmitry A. Kazakov
2020-10-01 22:13                                                 ` Randy Brukardt
2020-10-01 11:48                                         ` J-P. Rosen
2020-10-01 12:54                                           ` Dmitry A. Kazakov
2020-10-01  7:57                                 ` Paul Rubin
2020-10-01  9:26                                   ` Dmitry A. Kazakov
2020-10-01  9:46                                     ` Paul Rubin
2020-10-01 10:35                                       ` Dmitry A. Kazakov
2020-10-01 19:02                                       ` DrPi [this message]
2020-10-01 23:12                                         ` Paul Rubin
2020-10-01 21:54                                       ` Randy Brukardt
2020-10-01 23:14                                         ` Paul Rubin
2020-10-01 21:36                             ` Brian Drummond
2020-10-02  6:56                               ` Dmitry A. Kazakov
2020-10-02 18:34                                 ` Brian Drummond
2020-10-02 21:24                                   ` Paul Rubin
2020-10-06 23:54                                     ` Brian Drummond
2020-10-03  6:54                                   ` Dmitry A. Kazakov
2020-10-05 14:03                               ` Shark8
2020-10-07 11:56                               ` Olivier Henley
2020-10-09 12:35                               ` Olivier Henley
2020-10-09 14:41                                 ` Brian Drummond
2020-09-28 18:40                 ` Vincent Marciante
2020-09-28 20:28                   ` Dmitry A. Kazakov
2020-09-28 17:04               ` DrPi
2020-09-28 17:30                 ` Olivier Henley
2020-09-28 18:05                   ` Olivier Henley
2020-09-28 19:36               ` Shark8
2020-09-03 10:32 ` c+
2020-09-12  4:30 ` sumde121
2020-09-19 14:09 ` erchetan33
2020-10-01 22:21 Randy Brukardt
2020-10-02  6:55 ` Dmitry A. Kazakov
2020-10-03  3:09   ` Randy Brukardt
2020-10-03  6:42     ` Dmitry A. Kazakov
2020-10-03  7:44       ` Niklas Holsti
2020-10-03  8:16         ` Dmitry A. Kazakov
2020-10-03 10:44           ` Niklas Holsti
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