Some Xbox 360 and PS3 questions

[Liandry]

I would like to start a new thread about Xbox 360 and PS3. There is still some moments I didn't understood yet. I will try to ask questions by one and maybe someone can explan. Also would be interesting if some discusion starts here.
So question. Maybe someone haven't red this:
https://www.copetti.org/writings/consoles/xbox-360/
There in Organising the content section is info about Xbox Procedural Synthesis.

• Firstly, the CPU’s front-side bus was adapted so the GPU can directly fetch data from the CPU’s L2 cache (where the CPU may procedurally generate the geometry) in blocks of 128 Bytes (the size of a cache line).
• Secondly, a separate cached location was added into Xenon so the GPU can notify its current state to the CPU as fast as possible. Microsoft calls it the Tail pointer write-back and keeps both components in sync while the CPU updates the L2 cache and the GPU pulls from it. According to Microsoft, this routine provides a theoretical bandwidth of 18 GB/sec

As I know bandwith between CPU and GPU was 10.8 GB/s in each side, and here is info about 18 GB/s from CPU to GPU. How that is possible and is that info correct?

 

[Rootax]

Damn, I didn't know this website. A lot of interesting data everywhere. I've don't know the answers to your questions, but thanx for the url.

 

[function]

I would like to start a new thread about Xbox 360 and PS3. There is still some moments I didn't understood yet. I will try to ask questions by one and maybe someone can explan. Also would be interesting if some discusion starts here.
So question. Maybe someone haven't red this:
https://www.copetti.org/writings/consoles/xbox-360/
There in Organising the content section is info about Xbox Procedural Synthesis.

• Firstly, the CPU’s front-side bus was adapted so the GPU can directly fetch data from the CPU’s L2 cache (where the CPU may procedurally generate the geometry) in blocks of 128 Bytes (the size of a cache line).
• Secondly, a separate cached location was added into Xenon so the GPU can notify its current state to the CPU as fast as possible. Microsoft calls it the Tail pointer write-back and keeps both components in sync while the CPU updates the L2 cache and the GPU pulls from it. According to Microsoft, this routine provides a theoretical bandwidth of 18 GB/sec

As I know bandwith between CPU and GPU was 10.8 GB/s in each side, and here is info about 18 GB/s from CPU to GPU. How that is possible and is that info correct?

They are perhaps changing the direction of one side of the bi-directional bus for a period of time.

 

[davis.anthony]

This is where we need Sebbi as he's very experienced working on these systems.

 

[Zeross]

This is just taking into consideration the compression feature:

A previously mentioned feature very important to XPS is the addition of D3D compressed formats that we implemented in both
the CPU and the GPU. To get an idea of this feature’s usefulness, consider this: Given a typical average of 2:1 compression and an XPS- targeted 9 Gbytes/s FSB bandwidth, the CPU cores can generate up to 18 Gbytes/s of effective geometry and other graphics data and ship it to the GPU 3D core. Main memory sees none of this data traffic (or footprint).

source

 

[Liandry]

This is where we need Sebbi as he's very experienced working on these systems.

That's true. Is he still post here sometimes?

This is just taking into consideration the compression feature:

So as I understand CPU can give up to 18 GB/s but as data compresed then that is only 9 GB/s of bandwith?