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From: "Vladimir Olensky" <vladimir_olensky@yahoo.com>
Subject: Re: Apex vs GNAT on solaris
Date: 1999/12/07
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References: <82hiuj$74o$1@nnrp1.deja.com> <82hk5c$80p$1@nnrp1.deja.com>
 <82hob6$avp$1@nnrp1.deja.com>
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Date: 1999-12-07T00:00:00+00:00
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Robert Dewar wrote in message <82hob6$avp$1@nnrp1.deja.com>...
>In article <82hk5c$80p$1@nnrp1.deja.com>,
>  reason67@my-deja.com wrote:
>>     Start_Time := Ada.Calendar.Clock;
>>     Free (Last);
>>     Stop_Time := Ada.Calendar.Clock;
>
>This is completely hopeless methodology, of course you will
>not get useful results this way, the time for a Free is
>orders of magnitude faster than the clock resolution.


When I did some tests with GNAT 3.12p on Windows NT
I used Ada.Real_Time.Clock to measure elapsed time.

I do not know about  GNAT 3.11 for Solaris but
GNAT 3.12p Ada.Real_Time.Clock  gives one
nanosecond resolution on Windows NT (uses NT
high performance counter).
This information for particular platform could be
found in GNAT reference manual.
GNAT 3.11p for WinNT did not used NT high performance
counter.

In any case if OS has such counter it could be accessed
via assembler routine.

Here is a snippet from my code:

with Ada.Real_Time;
Procedure Test_Something;
   <...>
 use type Real_Time.Time;
   <...>
begin
  <...>
  Start_Time  := Ada.Real_Time.Clock;

  Do_Something (Number_Of_Iterations);
  -- contains loop which performs some action
  -- Number_Of_Iterations times

  Finish_Time  := Ada.Real_Time.Clock;
  Elapsed_Time := Ada.Real_Time.To_Duration (Finish_Time - Start_Time);
  <...>
end Test_Something;


Regards,
Vladimir_OLensky