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From: "(see below)" <news@findlayw.plus.com>
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Subject: Re: Ada.Execution_Time
Date: Tue, 28 Dec 2010 19:41:40 +0000
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Date: 2010-12-28T19:41:40+00:00
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On 28/12/2010 16:55, in article 1oq6oggi7rtzj.4u4yyq6m8r74$.dlg@40tude.net,
"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote:

> On Tue, 28 Dec 2010 16:27:18 +0000, (see below) wrote:
> 
>> Dmitri reports a modern computer with a timer having a resolution that is
>> thousands or millions of times worse than the CPU's logic clock.
> 
> You get me wrong, the timer resolution is OK, it is the system service
> which does not use it properly. In the case of VxWorks the system time is
> incremented from the timer interrupts, e.g. by 1ms. You can set interrupts
> to each 1um spending all processor time handling interrupts. It is an OS
> architecture problem. System time should have been taken from the real time
> counter.

Surely the interrupt rate does not matter. The KDF9 clock interrupted once
every 2^20 us, but could be read to the nearest 32 us. Can the clock you
speak of not be interrogated between interrupts?

> 
>> Why has this aspect of computer architecture degenerated so much, I wonder?
>> And why have software people not made more of a push for improvements?
> 
> The computer architecture did not degenerate. [...] It is
> usually the standard OS services to blame for not using these clocks.

I guess the second part of my question stands. 8-)

-- 
Bill Findlay
with blueyonder.co.uk;
use  surname & forename;