TEAM-ADA Archives

Team Ada: Ada Programming Language Advocacy

TEAM-ADA@LISTSERV.ACM.ORG

Options: Use Forum View

Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Reply To:
Date:
Tue, 7 Nov 2000 09:39:29 +0100
Content-Type:
text/plain
Parts/Attachments:
text/plain (57 lines)
Tom Moran wrote:

> > Presumably DELAY UNTIL is
> > implemented with an
> > interrupt. Could there be an overhead of some 10 or more
> > microseconds
>   I would be astonished if Windows did short delays with interrupts.
> >From my timings, it takes 4.9 mics just to do the OS call etc for "T :=
> Ada.Calendar.Clock" (and since Gnat apparently uses the same (the only)
> clock for Real_Time and Calendar, that would be same). Most Windows
> calls specify times in milliseconds (though that is often misleading
> about actual precision).  The thing that ticks at .8 mics is accessed
> via a "QueryPerformanceCounter" call - I don't think they really think
> of it as a general purpose clock at all.
> > So would be surprising in a
> > realtime
> > operating system, though it is not surprising in a commercial
> > operating
> > system.
>   My timings are running on Windows 95, which is the latter.
> Does any version of Windows actually do timing and interrupts in 1
> microsecond?

>>
in WIN NT/Win2K  BOOT.ini  file, this following variable is supposed to set
some interesting atomic beat.
  /TIMERES=  On the multiprocessor HAL (HALMPS.DLL) this option will set the
resolution of the system timer. The argument is a number interpreted in
100's of nanoseconds, but the rate will be set to the closest resolution the
HAL supports that is not larger than the one requested. The HAL supports the
following resolutions:
 100's of nanoseconds  =>   milliseconds
                9766                   .98
              19532                   2.0
              39063                   3.9
              78125                   7.8
 The default resolution is 7.8ms. The system timer resolution affects the
resolution of waitable timers. Example:   /TIMERES=9000 would set the timer
to a resolution of .98ms. (not better than Alsys many years ago (around
0.87))

This information is available on http://www.sysinternals.com/bootini.htm
Anyone reached  this on windows based single processor machines ?

Cheers.


--
-- Jean-Philippe Vassilakis
-- SOFIE & Ellipsometers software
-- Jobin-Yvon Thin Films Group
-- mailto:[log in to unmask]
-- http://www.JobinYvon.com/produit/thinfilms/Thin_films.htm
-- 7 Route d'Egly    91290 Arpajon France
-- Tel: +33 (0)1 6490 9365  Fax: +33 (0)1 6083 9183
--

ATOM RSS1 RSS2