Common problems with Ubuntu

[Micha Feigin]

On Sat, 15 May 2010 08:19:03 +0000
Tzafrir Cohen <tzafrir at cohens.org.il> wrote:

> On Fri, May 14, 2010 at 10:59:37PM +0300, michf at post.tau.ac.il wrote:
> 
> > I do still have quite a few qualms with it though on other regards. I'm deep
> > into GPU computing at the moment (Cuda) and what Windows vista and 7 did to the
> > graphics driver model is a classic example of Microsoft's approach for world
> > domination. The operating system is actually managing a virtual memory on the
> > graphics card behind the graphics driver back.
> > 
> > although designed to assure the DWM can always have enough memory, this causes
> > a bunch of unexpected and uncontrolled performance and feature issues.
> 
> What does that mean? Latest Linux version also manage the card's virtual
> memory.
> 

No it doesn't. Driver manages the video card memory. On a 4GB card you can make
a single 4gb allocation and when the memory runs out it runs out, allocation
fails. No memory goes in and out of the card without explicitly asking the
driver to do so.

With Windows 7 the video driver does not see the video card memory. Windows
implements a swap on the video card and swaps video memory in and out to system
memory behind your back. You can over commit the card. Maximum allocation is
~1gb even when the card has 4gb, if you use too much memory performance drops
suddenly. General graphic performance can be half that of Windows XP in some
situations and when swapping performance can drop to under 10% of the full
performance.