[Info-vax] OT: Arun Kishan

[FredK]

"Paul Sture" <paul.nospam at sture.ch> wrote in message 
news:paul.nospam-C449E4.14074916012010 at pbook.sture.ch...
> In article
> <dec96c96-1ba6-4f28-af8f-099e46fa695b at m26g2000yqb.googlegroups.com>,
> John Wallace <johnwallace4 at yahoo.co.uk> wrote:
>
>> "Critical for system reliability" was important in the original NT
>> design (the one that outsiders saw as NT3.x) but afaik was quickly
>> (and quietly) sacrificed.
>
> I don't remember the sacrifice being all that quiet. Rather I recall
> dragging the graphics into the kernel being actively promoted as a
> performance benefit.
>

Putting it in context, graphics performance has always driven bend-the-rules 
programming.  The early days used direct rendering to simple graphics (like 
frame buffers) or a relatively efficient indirect rendering that queued 
drawing commands (directly, or via a simple IO call) to DMA hardware.  The 
complexity came in the form of finding a fast/simple way to coordinate 
access to the HW between the callers as graphics cards appeared without 
atomic drawing commands.  X11 simplified that by having all graphics access 
be done by a seperate process (the X11 Server) which would have complete 
control of the HW - but at the cost of having to encode and pass the drawing 
commands through a protocol pipe and a context switch.  3D made it even more 
complex because of the amount of HW context needed for a graphics call.  But 
the belief was that CPUs were getting faster and faster and that the 
overhead would eventually be noise.  The same thing with Windows.  NT 
implemented all kinds of clever things to make the overhead of the graphics 
call to be "small" - but it still came at the cost of a context switch. 
So, VWS was faster on the same HW than X11, and pre-NT Windows was faster on 
the same HW as NT.  It turns out that in the case of graphics, raw speed is 
was the bottom line to users.  So NT changed things, and many X11 
implementations hacked in direct rendering (mostly 3D, but sometimes even 
2D) support.

Today, except for the truly high-end (esp 3D) we've reached a point where 
indeed that overhead is mostly "noise".  Things are so fast that even common 
2D text output is anti-aliased on many Linux implementations.