Xbox One (Durango) Technical hardware investigation

Or you could highlight it like this:

Anyway my point is that its not really OR, they are AND so you cant really simply divide it like that.

 

Well the XB1 does seem designed to have special function hardware reduce the need for GPGPU usage.

 

Such as? the only thing I can see is audio which is generally a CPU job and not a huge one at that.

 

Agreed.

 

What I really miss is an explanation how the paper specs require a 215W PSU. I would really want to understand where I made a mistake in my assumption.

 

Perhaps the safety margin with efficiency margin and maybe there being no benefit in making a smaller rated PSU? Sort of like the cost of making a 150GB mechanical drive is nearly the same cost as making a 215GB mechanical drive. At some level the costs no longer decrease. (I don't know, just grasping as wild ideas.)

Or perhaps it's safety margin with efficiency margin with all USB3 ports loaded. *shrug*

 

It kinda depends on how you want to split it up in the sense that giving devs SHAPE et al means they have a place to do advanced mdoern audio calculations, wehreas on PS4 they might have to use those CU's for that kinda stuff. On the one hand, those extra CU's can be used for other general purpose stuff too. Then again, general processors require much larger processing overhead compared to specialized, targeted, fixed function processors. So the end result is having fixed function stuff like SHAPE keeps X1's CU's presumably more open for business in terms of other types of calculations (non-audio stuff). So do we give them credit on that front for leveraging SHAPE to make GPGPU usage of their CU's more targeted towards non-audio stuff? It's kinda in the eye of the beholder imho.

 

Actually, it's quite logical. It's the same reason ATI gave Dave the Xenos interview when the Xbox 360 was launching. The architects didn't think the design was getting the credit it deserved.

It was likely in doubt for people who remembered how the edram in the xbox 360 worked and were afraid of the same limitation. Also, the Sea Islands family is CI. SI is Southern Islands.

Your statement is true for PCs, but not for consoles.

 

No, I speculated it might be related to the size of the logic elements which could have altered the timings (distance between elements may have affected quantum parameters known to govern transistor timings). The timings is what I was told about a priori and what was in line with the original DF article on the subject. It also fit in well with the math about the 7/8 cycles theory.

Those access patterns are a result of the overlap in timings. You have to be able to fit the timings into a cycle to get both reads and writes in that window but if the timings are slightly longer than half the cycle width you will eventually shift the pairs of ops to straddle a cycle in such a way that only 1 of them fits inside.

That article confirmed just about everything I've been arguing over the past 6 months or so. Only other thing I was hoping to see was a link between GPU clock boost (its magnitude, not its payoff vs extra CU's) and the eSRAM bandwidth timings. Such is life.


Who was it...Engadget? Were they the ones saying the 7790 was basically the X1 GPU? Sounds like they deserve props there. That was pretty close to being spot on. I also wanna see them explain the thin black arrow connecting the eSRAM to the CPU on their HotChips presentation, or have we figured that out already?

 

Apparently they have separate ports for reads and writes and as long as there is no bank conflict, they can carry out both simultaneously. That's probably all and a technique almost as old as SRAM itself. And it doesn't require techniques nobody has ever heard of or defies common rules of logic design. MS probably just confused themselves with their spec given to devs.

 

They found out that upping the clock was better than having 2 more CU.
It didn't matter at all that 2 additional CU cost more money while more hz cost nothing .

 

You could add 1000 cu, but if the CPU is the bottleneck, whats the point?

 

That quote could be misleading. MS evaluated current software and found the CPU was a bottleneck (although why Jaguar then?). However, if the software isn't optimised for the hardware (compute), then the bottlenecks seen may not be representative of bottlenecks devs will experience in future. We may find that the CPU has enough grunt to drive more CU once more workloads are shifted off the CPU onto the GPU. Might. I'm only identifying it as a weakness in the argument that states frame-drops are typically CPU bottlenecks. Devs can write any sort of engine that could be throttled by any subsystem. Having said that, it's worth noting the ERP also sees the CPU as the primary bottleneck, although again coming off current software designs. A lot depends on how things change on the software side in the coming years.

 

I presume it's the most commonly produced psu, and therefore the cheapest.

All the talk about power efficiency though ... They have a huge box, an external brick .... Perhaps their box is going to be the quietest, at least?

 

Is 16ROPS going to become a huge issue?

 

Basically, the BW version of double buffering except people usually don't claim they have 512kb of cache when they're double buffering 256kb.

 

Then you go back and re-write your code to remove the bottleneck, and it's not a 1000 vs 12 CU

It's a great interview that surely demonstrates that Microsoft did not make choices blindly and it's obvious that they think that the way they went with there hardware was the correct one. I would be surprised to read a interview without them defending themselves and coming up with good arguments.

 

a good interview. kind of weird it took people on forums questioning the esram for ms to talk about it nad they were shocked that people questioned it. they never explained it so people were going to question it duh.

the dynamic resolution stuff sounds awesome! im not trying to turn this into a versus but wouldn't this mean that multiplatform games would be equal to each other? being able to dynamically change the resolution would mean solid framerates right? if the hud stays the same resolution thanks to display planes then xbox games might perform better than the competition if the compeitition drops framerates every once in a while due to not having hardware for dynamic resolution scaling.

i think thats a bigger deal than anything else no?

also the memory access stuff with the crossbar, is that like how ps3 could access both the gddr3 and xdr? would that mean theres a latency penalty for xbox one?

 

What I don't understand with the dynamic resolution is how do you know when to drop the resolution and by the time you know wouldn't it be too late? Is there some sort of counter indicating time to render the frame and you need to make the decision on the resolution at the start of the rendering of the frame?

 

Did you miss that part where DF mentioned Wipeout HD, a PS3 game? This technique is not new.

Well why is your resolution dynamically dropping if you are CPU bound? It is the GPU that is the issue in these cases.