NV SONY怎么了，PS3又传来噩耗~

DDwindzero

The PS3 GPU is not fast enough yet

It appears


By Charlie Demerjian in Taipei: 星期日 04 六月 2006, 16:19

SOME VERY INTERESTING tidbits have emerged about the PS3 GPU during my flight to Japan yesterday. It seems like the second gen dev kits were running nowhere close to full speed or spec. How close were they? Fairly.
Documents shown to us on the trip showed that there were two versions, labeled 'CEB' and 'DEH'. The earlier CEB has a chip called CBE (yes, I know) connected to main memory and to a south bridge. The SB is then connected to a chip labled 'NV4x' over a PCIe link. The upcoming version DEH has the CBE and main memory, but the NV4x/SB combo is replaced by the RSX. If you wanted to know what makes RSX more than a GPU, it looks like it is SB functionality.

The slightly more curious bit, encouraging and disturbing at the same time, is the current state of RSX. The disturbing part is that the slide I was shown had "Current DEH's aren't final spec or speed" in bold letters. Speed, OK, but not final spec at this point in time leaves precious little room for debugging before the console release. On a different note the current ones are running the RSX core at 420MHz with 550 expected for launch. Memory is set at 600MHz with 700 hoped for as final.

It looks like SoNVidia is most of the way there with RSX development, 80% of the clock, more for memory. One more spin, most likely another round of dev kits, and the code monkeys will know what they are facing. µ


首先是即将到来的新版开发机~按计划应该是最终版了~但RSX速度只有420MHZ，不是原计划的550MHZ; XDR内存速度为600MHZ，不是原计划的700MHZ；SONY特别注明该版本开发机依然不是最终版，但问题是如果现在还不拿出最终版开发机，游戏开发商根本就没有时间做最后调试工作


PS3 hardware slow and broken

In words and pictures


By Charlie Demerjian in Taipei: 星期一 05 六月 2006, 03:35

AFTER BREAKING THE news to me about PS3 RSX speeds earlier on the flight to Japan, my row-mate said 'if you think that's interesting, wait till you see this. Cell is hurting, badly'.
For those of you that believe in religions with karmic tendencies, scoops like this meant one of two things, the wings of the plane are about to fall off and I am going to die in a fiery ball, or worse yet, the movie selection will be worrisome. Cell memory access appears to be broken, RSX has half the triangle setup rate of the ATI chip in XBox360, and the true horror, Big Momma's House 2 and a Queen Latifa movie.

With the movie selection still making my brain throb from the glances I caught, I furiously took notes on what the source was saying. He started out saying that the RSX can only write about half as much vertex data as it can fetch, not an ideal situation by any stretch, but survivable.

Then came the horrible news, RSX appears to be limited to setting up 275 Million triangles/second, anemic compared to the 500+ million in XBox360. When asked about this apparent thumping dished out by MS, the reply from one notable ISV relations boffin was a terse 'What a Piece of Junk'. Talk about a steak in the heart.

Half the triangle setup capability in the PS3, could things get worse? Yes, far far worse, how about another disparity of three orders of magnitude? No, I am not joking, looking at Sony's own figures, Cell appears to be pretty badly broken.



For main memory, it looks like Cell has about 25GBps of main memory bandwidth, and RSX is about 15-20GBps. Achievable bandwidth is between about two thirds of that and nearly 100%, clearly the elves in the caves surrounding Rambus central did something right with XDR. That is the happy news.

For local memory, the measured vs theoretical bandwidth is missing, I wonder why? RSX is at a solid 22.4GBps for both read and write, good job there green team. Then comes the blue team with Cell. Local memory write is about 4GBps, 40% of the next slowest bandwidth there. Then comes the bomb from hell, the Cell local memory read bandwidth is a stunning 16MBps, note that is a capital M to connote Mega vs a capital G to connote Giga. This is a three order of magnitude oopsie, and it is an oopsie, as Sony put it "(no, this isn't a typo...)".

If you can write at 250x the read speed, it makes Cell local memory just about useless. That means you do all your work out of main memory, and the whole point of local is, well, pointless. This can lead to contention issues for the main memory bus, and all sorts of nightmarish to debug performance problems. Basically, if this Sony presentation to PS3 devs shown to us is correct, it looks like PS3 will be hobbled in a serious way.

The next slide goes on to say "Don't read from local memory, but write to main memory with RSX(tm) and read it from there instead", and repeats the table numbers. This is very very bad. The number of times the presentation goes on to say that it is correct, and the lack of anything like "this will be fixed by production steppings, so take measures X, Y and Z" say to me that it is not a fixable snafu. Remember at E3 when I said that the PS3 demos there were object sparse? Any guesses why?

Someone screwed up so badly it looks like it will relegate the console to second place behind the 360. All the devs I talked to were lukewarm on the 360 architecture but universally negative on the PS3. Revelations like this go a long way to explain why you keep hearing about simmering problems from the Sony devs.

You end up with a console with half the triangle setup rate of the 360, a crippled CPU that is a bitch to program, and tools that are atrocious compared to the 360. To make matters worse, you have an arrogant set of execs telling us that twice the price is worth it for half the power, a year late. If it isn't already too late, Sony had better do something about this recto-cranial inversion or it may very well sink the console. µ



消息接连不断~RSX的多边形生成速度被限制在2.75亿/秒~远低于X360的5亿/秒……RSX问题不断，但更坏的消息来自内存，PS3 怪异的两种内存混合结构也有大麻烦~


RSX怎么还没有搞定~ cell+RSX现在看来又这么惨~
知情的大大们，能否说明一下目前的状况 ~

Edison

这个不是讨论过了吗？

http://we.pcinlife.com/thread-567205-1-1.html