All of lore.kernel.org
 help / color / mirror / Atom feed
From: David Kastrup <dak@gnu.org>
To: linux-rt-users@vger.kernel.org
Subject: Re: preempt rt in commercial use
Date: Wed, 15 Sep 2010 17:38:34 +0200	[thread overview]
Message-ID: <87k4mnhv9h.fsf@lola.goethe.zz> (raw)
In-Reply-To: 4C90D392.8040808@us.ibm.com

Nivedita Singhvi <niv@us.ibm.com> writes:

> At some stage this might have been a pretty good response time.  But
> HW improves by leaps and bounds, and what was considered "fast" or
> "real-time" 25 years ago might be your average vanilla desktop box
> speed of today.

I think you are confused.  "fast" and "realtime" are quite unrelated.
The computers used aboard ancient space craft are abysmally slow
compared to today's desktop computers, but certainly operate in
realtime.

It does not matter whether one system can run circles around the other
one as long as any given circle can't be guaranteed to complete in a
specified amount of time.

Realtime recording systems, for example, can't actually be writing to
high performance file systems unless they can work with preallocation.

Hard realtime is not reasonably possible for a lot of tasks on a general
purpose computing device.  But there is often a lot you can do to help
it give a better shot at things.

-- 
David Kastrup


  parent reply	other threads:[~2010-09-15 15:38 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-14  8:10 preempt rt in commercial use Raz
2010-09-14  9:04 ` Rolando Martins
2010-09-14  9:10   ` Raz
2010-09-14  9:20     ` Rolando Martins
2010-09-14  9:17 ` Nikita V. Youshchenko
2010-09-14  9:24   ` Raz
2010-09-14  9:44     ` Robert Schwebel
2010-09-14 12:16       ` Armin Steinhoff
2010-09-14 13:04         ` Daniel James
2010-09-14 13:08         ` Pradyumna Sampath
2010-09-14 22:11           ` Nivedita Singhvi
2010-09-14 13:09         ` Klaas van Gend
2010-09-14 13:17         ` David Kastrup
2010-09-14 13:37           ` Darcy Watkins
2010-09-14 13:58         ` Patrice Kadionik
2010-09-14 14:21       ` Jeff Angielski
2010-09-14 14:30         ` Nikita V. Youshchenko
2010-09-14 14:49           ` Jeff Angielski
2010-09-14 22:20             ` Nivedita Singhvi
2010-09-15  7:48               ` Armin Steinhoff
2010-09-15 14:09                 ` Nivedita Singhvi
2010-09-15 14:45                   ` Pradyumna Sampath
2010-09-16 10:17                     ` Daniel James
2010-09-16 10:35                       ` Pradyumna Sampath
2010-09-16 15:19                       ` Raz
2010-09-15 15:38                   ` David Kastrup [this message]
2010-09-15 16:02                     ` Nivedita Singhvi
2010-09-15 16:20                       ` David Kastrup
2010-09-16  0:44                         ` Steven Rostedt
2010-09-16 15:27                           ` Nivedita Singhvi
2010-09-16 17:30                             ` Steven Rostedt
2010-09-16 19:27                               ` Armin Steinhoff
2010-09-16 19:38                                 ` Steven Rostedt
2010-09-15 13:33             ` Thomas Gleixner
2010-09-14 14:44         ` Pradyumna Sampath
2010-09-15 12:48           ` Sergio Ruocco
2010-09-15 12:53             ` Pradyumna Sampath
2010-09-15 14:58             ` Paul E. McKenney
2010-09-15 16:27             ` Sven-Thorsten Dietrich
2010-09-16  0:49               ` Steven Rostedt
2010-09-16  5:06                 ` David Kastrup
2010-09-14 14:56         ` Armin Steinhoff
2010-09-14 15:42         ` Patrice Kadionik
2010-09-14 17:38         ` Gregory Haskins
2010-09-14 22:09           ` Nivedita Singhvi
2010-09-15  6:22             ` Patrice Kadionik
     [not found]               ` <4C90CF71.2050205@us.ibm.com>
2010-09-15 13:56                 ` Patrice Kadionik
2010-09-15 14:08               ` Steven Rostedt
2010-09-14 10:06   ` Klaas van Gend
2010-09-14 11:00     ` David Kastrup
2010-09-14  9:28 ` Pradyumna Sampath
2010-09-14 14:13 ` Reagan Thomas
2010-09-15  7:09   ` AW: " Lukas Redlinger
2010-09-15  3:38 ` jordan
2010-09-15  8:59   ` Klaas van Gend
2010-09-15 11:03     ` TinxCore and PREEMPT_RT Armin Steinhoff
2010-09-16  9:38       ` Armin Steinhoff
2010-09-16 10:18         ` David Kastrup
2010-09-16 11:25           ` Mike Galbraith
2010-09-16 11:51           ` Armin Steinhoff
2010-09-15 14:03     ` preempt rt in commercial use Nivedita Singhvi
2010-09-15 17:29       ` Reagan Thomas
2010-09-16 10:39         ` Daniel James
2010-09-16 20:47           ` jordan
2010-09-16 10:07   ` Daniel James
2010-09-16 20:37     ` jordan

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87k4mnhv9h.fsf@lola.goethe.zz \
    --to=dak@gnu.org \
    --cc=linux-rt-users@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.