Sender: root AT delorie DOT com
Message-ID: <3767CB78.FC5F36A6@inti.gov.ar>
Date: Wed, 16 Jun 1999 13:06:16 -0300
From: salvador <salvador AT inti DOT gov DOT ar>
Organization: INTI
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To: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
CC: djgpp AT delorie DOT com, allegro AT canvaslink DOT com, balug-lst AT balug DOT org DOT ar
Subject: Re: Compilers comparisson, some opinions about the generated , assembler
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Reply-To: djgpp AT delorie DOT com

Eli Zaretskii wrote:

> On Wed, 16 Jun 1999, salvador wrote:
>
> > 2) If I run only one task in Win95 (and the scheduler didn't get crazy) I get
> > the same speed in W95, the difference is too small (under 2%)
>
> My notion of slow-down when running on Windows is taken from configuring
> and building large GNU packages, those where it takes more than 10 minutes
> to run the configure scripts and Make.  Overall, on the same machine which
> is higly optimized for DJGPP programs both in DOS and in Windows, I
> usually get 30%-40% slow-down for the same task when running from
> Windows.  That's running only one active DOS box under Windows, and no
> other Windows programs.  For example, what takes 20 minutes from Windows
> would usually take about 12 minutes from DOS.

Interesting, I never saw important differences in tasks that consumes only CPU (no
disk at all).

> I have never been able to figure out just what it is in Windows that takes
> so many CPU cycles.  Interestingly enough, if I do something else while
> the compilation runs, like read my mail with Emacs, or type some code
> into the editor, the compilation time is unchanged.  So apparently
> multi-tasking other virtual machines is NOT what steals the CPU cycles.

In fact I think the problem isn't related to CPU cycles. I remmember that first
time I tried my sound player under Windows I was surprised about the small
difference in the frame rate (under 10%, usually around 4 and 5%). This program
uses direct memory access to screen and the Sound Blaster DSP, also polls keyboard
and mouse.
I think you are hiting the problem I experimented (more than 15%), in fact once I
had this problem I wasn't able to recover the full speed. For some reason the
scheduler was giving this CPU percent to other process.
But that isn't the common case.

Greetings, SET

--
Salvador Eduardo Tropea (SET). (Electronics Engineer)
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