[clug] Modern laptops, nVidia, Optimus and Linux

David Austin david at d-austin.net
Wed May 4 19:24:55 MDT 2011

On Thu, May 5, 2011 at 11:03 AM, Hugh Fisher <hugh.fisher at anu.edu.au> wrote:

> David Austin wrote:
>> <if I ran the world>
>> I must say I'm surprised by the while DisplayPort/Thunderbolt thing.
>> I'm all for higher communication speeds as a general rule, but I
>> don't understand why they don't restructure the system to eliminate
>> the difficult high-bandwidth link.
>> The graphics "card" should be integrated with the monitor.
>> </if I ran the world>
> Putting the graphics card in the monitor would increase the
> bandwidth required, not decrease it. PCIe 2 with 16 lines
> is 64Gbits/sec, DisplayPort only needs 17Gbits/sec. Some
> graphical/number crunching programs prefer having two cards
> available.

Pumping out pixels is a nice predictable data stream with
> a fixed upper bound determined by monitor resolution and
> frame rate. CPU <-> GPU bandwidth is a lot more varied and
> the high end is very demanding.

I think you've made my point for me with the last parts of both
paragraphs.  Yes, for number crunching and (high end) games
the CPU <-> GPU bandwidth is high (though I wonder how
many games saturate PCIe).  But for the vast majority
of uses this is not the case.

For example, blu-ray video is around 40MB/s - far lower than
17Gbits/sec or 64Gbits/sec.


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