new Far Cry 360 interview

[turkish a. punkass]

http://interviews.teamxbox.com/xbox/1485/Far-Cry-Instincts-Predator-Interview/p1/

"So far, no game has yet taken advantage of the three cores found in the Xbox 360 CPU and in the press release you claim that Predator takes advantage of Xbox 360's multi-core architecture. Can you tell us how?

Jean-Francois Dugas: Yes, Far Cry Instinct Predator uses the three Xbox 360’s processing cores. As said previously, our team will use the latest technologies to improve the game such as the Shader 3.0 and the new HD possibilities offered by the 360. All these new graphical features will improve the immersion. "

how does everyone know that no other game is using all three cores? has there been documented proof of this, or is it just hopeful speculation due to the somewhat dissapointing nature of current "next gen" visuals?

 

[mckmas8808]

I know for sure that some devs said that they have used all three cores. COD2 used all three cores. WTF are these guys talking about?

 

[blakjedi]

As does Geometry Wars...

 

[Griffith]

I know for sure that some devs said that they have used all three cores. COD2 used all three cores. WTF are these guys talking about?

we have 3 cores, 6 threads, 3 VMX units

so using all the cores can mean:

3 cores - 3 threads - 0 VMX

3 cores - 4 threads - 0 VMX

3 cores - 5 threads - 0 VMX

3 cores - 6 threads - 0 VMX


3 cores - 3 threads - 1 VMX

3 cores - 4 threads - 1 VMX

3 cores - 5 threads - 1 VMX

3 cores - 6 threads - 1 VMX


3 cores - 3 threads - 2 VMX

3 cores - 4 threads - 2 VMX

3 cores - 5 threads - 2 VMX

3 cores - 6 threads - 2 VMX


3 cores - 3 threads - 3 VMX

3 cores - 4 threads - 3 VMX

3 cores - 5 threads - 3 VMX

3 cores - 6 threads - 3 VMX


the best use is, of course, 3 core - 6 threads - 3 VMX, this will happen IMO with 3 gen games, so the actual claim are, imo, near the worse situation, 3 cores - 3 threads - 0 VMX Units, even a 2 cores - 4 threads - 2 VMX is better than this

so don't let the PR BS gain hype

 

[barnak]

,m,m

 

[czekon]

GRAW is using 3 cores too AFAIR

 

[groper]

Actually , according to devs , GRAW uses 6 threads.
2 of them help with rendering ( hdr, post-effects etc) and 4 for the rest game code ( AI , Physics ,game controls etc)

 

[czekon]

Actually , according to devs , GRAW uses 6 threads.
2 of them help with rendering ( hdr, post-effects etc) and 4 for the rest game code ( AI , Physics ,game controls etc)

that is why GRAW is looking so great

 

[Griffith]

Actually , according to devs , GRAW uses 6 threads.
2 of them help with rendering ( hdr, post-effects etc) and 4 for the rest game code ( AI , Physics ,game controls etc)

Ok I get the thing, but how can they use the cpu for hdr, when the frame buffer is in the eDRAM?

this is clearly a bulls.

they say that uses the 80-90% of the console, this is imo another BS, a lot of years was required to exploit the 80-90% of power from a simple console as xbox1 (look at Black, for example)
x360 have a complex design, with a very complex cpu, thay are lying, only PR

 

[AlNom]

Ok I get the thing, but how can they use the cpu for hdr, when the frame buffer is in the eDRAM?

Way back when the developer mentioned that in an interview, I believe others came to the conclusion that it was helping out with tone-mapping. It was one of the more respected members here who came up with that explanation... can't recall the thread unfortunately.

 

[groper]

Way back when the developer mentioned that in an interview, I believe others came to the conclusion that it was helping out with tone-mapping. It was one of the more respected members here who came up with that explanation... can't recall the thread unfortunately.

http://www.beyond3d.com/forum/showthread.php?t=26487&page=2 :smile:

they say that uses the 80-90% of the console, this is imo another BS, a lot of years was required to exploit the 80-90% of power from a simple console as xbox1 (look at Black, for example)

Using the 6 threads and 3vmx (or using 2 threads and 7 SPE's ) doesnt mean that they exploit the 90% of the power of the console.
It depends on how effectively they use them.

 

[Titanio]

the best use is, of course, 3 core - 6 threads - 3 VMX, this will happen IMO with 3 gen games

Not a major point, perhaps, but It all depends on what your utilisation is like. If a single thread on a core is using the core well - perhaps such that a second thread wouldn't get much of a look-in at all - then a single thread could be as "good" as two on the core. It's probably easier in most cases to get good utilisation with two threads, though.

I'd also say that in most cases core-usage involves VMX, currently, or I'd hope so anyway.

 

[AlNom]

I'd also say that in most cases core-usage involves VMX, currently, or I'd hope so anyway.

Sorry, I'm not versed in VMX/coding/usage. What is VMX used for/could be used for...or what is it meant to do

 

[Titanio]

Sorry, I'm not versed in VMX/coding/usage. What is VMX used for/could be used for...or what is it meant to do

I'm sure someone else could provide a better description, but VMX is a SIMD engine (Single Instruction, Multiple Data). SIMD means you execute the same instruction on multiple data elements in parallel. A common application would be 4-component vectors, 4 floating point numbers defining a vector. VMX lets you operate on each component simultaneously, in parallel. Vectors come up a lot in games, naturally, or data can be packed into vectors to take advantage of VMX/SIMD parallelism.

 

[czekon]

120 new screenshots

 

[Guden Oden]

we have 3 cores, 6 threads, 3 VMX units

so using all the cores can mean:

Thanks for wasting a lot of space stating the obvious with a big redundant list...

the best use is, of course, 3 core - 6 threads - 3 VMX, this will happen IMO with 3 gen games

Actually it won't ever happen, because each core is only double-issue. While there are four execution units (2 int, FP, VMX), only 2 of them can actually process anything each clock cycle, and there are additional exclusions as well. For example, the two int units aren't symmetrical, and it's quite possible that some FP/VMX instructions can't be paired up either etc.

Furthermore, each core will only ever execute instructions from one thread at a time, so using 6 rather than only 3 hardware threads doesn't neccessarily equate in greater performance all the time, especially as you will have as many as double the amount of threads fighting over the same 1MB L2 leading to thrashing.

so the actual claim are, imo, near the worse situation, 3 cores - 3 threads - 0 VMX Units, even a 2 cores - 4 threads - 2 VMX is better than this

What on EARTH are you talking about? This is absolute nonsense. You seriously believe FC 360 has zero VMX use?

 

[Tap In]

I'm so confused.


Far Cry, GR: AWF or BF2?

 

[czekon]

I'm so confused.


Far Cry, GR: AWF or BF2?

IMO

 

[AlNom]

VMX explanation

Thank you

 

[Lysander]

Furthermore, each core will only ever execute instructions from one thread at a time, so using 6 rather than only 3 hardware threads doesn't neccessarily equate in greater performance all the time, especially as you will have as many as double the amount of threads fighting over the same 1MB L2 leading to thrashing.

But there is a difference. I found pdf on net: Unsigned Xbox 360 Developer Best Practices

threads

• Multithread your game engine. Single-threaded games use only a third of the potential processing power of the system.
o Prefer using native Windows thread APIs and synchronization primitives. Xbox 360 supports similar APIs.
o A simple architecture for multithreading on Xbox 360 uses one thread for world updates and another thread for graphics processing. An additional CPU core can be used for audio, decompression, geometry generation or other game tasks.
o Another way to utilize additional cores is with OpenMP. OpenMP is supported in Visual Studio 2005.

and L2

• Access memory carefully. As is typical with high-performance CPUs, memory latency can be a significant bottleneck.
o Optimize for the L2 cache. Xbox 360 has a 1MB L2 cache. Think of RAM as a fast hard drive rather than as infinitely fast memory.
o Avoid walking linked-lists or any other data structure that has nodes spread across memory. Avoid walking any large data structure more than once per frame. Prefer contiguous data structures, like arrays.
• Prefer calculating data to loading it. The Xbox 360 CPU is a mathematical monster. Avoid code that’s special-cased to skip heavy duty math. In particular, avoid floating-point comparisons and avoid converting or casting data from int to float or vice-versa.