From: Robert Dewar <robert_dewar@my-dejanews.com>
Subject: Re: delay until and GNAT - expand
Date: 1999/05/11
Date: 1999-05-11T00:00:00+00:00 [thread overview]
Message-ID: <7h82qm$bq$1@nnrp1.deja.com> (raw)
In-Reply-To: rracine.13.0007AF82@draper.com
In article <rracine.13.0007AF82@draper.com>,
rracine@draper.com (Roger Racine) wrote:
> Note that I said, "given a good real-time operating system".
> That does not include any form of Unix (with the possible
> exception of LynxOS and any other real-time versions; I have
> not looked at their documentation recently).
I do not believe that the estimate of one microsecond latency
for a delay is anywhere near achievable for any of the typical
operating systems or executives that are used today for typical
real time systems. Roger, do some measurements if you want to
challenge this. Most certainly Lynx, which I know well cannot
begin to achieve this performance. Modern RISC machines have
a lot of state to save and restore, and of course context
switches typically involve cache switch overs which waste
even more time.
Certainly in all measurements we have done on GNAT, the time
spent in pthreads calls completely overwhelms all the time
in the GNAT runtime itself.
Probably the best case is to run VxWorks on a really fast
machine, I will see if I can get some measurements for this.
--== Sent via Deja.com http://www.deja.com/ ==--
---Share what you know. Learn what you don't.---
next prev parent reply other threads:[~1999-05-11 0:00 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-05-05 0:00 delay until and GNAT isaac buchwald
1999-05-05 0:00 ` David C. Hoos, Sr.
1999-05-05 0:00 ` dennison
1999-05-06 0:00 ` Buz Cory
1999-05-06 0:00 ` Robert Dewar
1999-05-06 0:00 ` delay until and GNAT - expand isaac buchwald
1999-05-07 0:00 ` Roger Racine
1999-05-08 0:00 ` dewar
1999-05-10 0:00 ` Context switching (was: delay until and GNAT) Nick Roberts
1999-05-11 0:00 ` Robert Dewar
1999-05-11 0:00 ` Tarjei Tj�stheim Jensen
1999-05-11 0:00 ` Robert Dewar
1999-05-11 0:00 ` David Brown
1999-05-11 0:00 ` Robert Dewar
1999-05-10 0:00 ` delay until and GNAT - expand Roger Racine
1999-05-10 0:00 ` Joel Sherrill
1999-05-11 0:00 ` Robert Dewar [this message]
1999-05-11 0:00 ` dennison
1999-05-11 0:00 ` isaac buchwald
1999-05-11 0:00 ` dennison
1999-05-12 0:00 ` Robert Dewar
1999-05-10 0:00 ` Roger Racine
1999-05-11 0:00 ` Robert Dewar
1999-05-11 0:00 ` dennison
1999-05-11 0:00 ` Robert Dewar
1999-05-12 0:00 ` delay until and GNAT - where to get the info isaac buchwald
1999-05-12 0:00 ` Robert Dewar
1999-05-11 0:00 ` delay until and GNAT - expand Roger Racine
[not found] ` <rracine.14.00 <rracine.15.000968A0@draper.com>
1999-05-11 0:00 ` Robert Dewar
[not found] ` <rracine.14.00 <rracine.17.0007DA28@draper.com>
1999-05-12 0:00 ` dennison
1999-05-12 0:00 ` Roger Racine
1999-05-06 0:00 ` delay until and GNAT Roger Racine
1999-05-10 0:00 ` Nick Roberts
1999-05-11 0:00 ` Context Switching Nick Roberts
1999-05-11 0:00 ` Robert Dewar
1999-05-11 0:00 ` Robert I. Eachus
1999-05-12 0:00 ` dennison
replies disabled
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox