The 8th SPE.

[London Geezer]

The 8th SPE should be regarded as not there.

It would be like putting a co-processor in PS3's from 2009 and expect games to support it... How would the millions of PS3 owners without the new chip feel?

Having said that, depending on how to-the-metal we'll be able to get with Linux, some people might find a way to softmod the Cell chip to enable the SPE (at their own risk!), much like people have unlocked disabled shader units in low-end GPUs to turn them into GPUs that are similar to the higher end of the same line with various levels of success, due to the fact that depending on the line, the only difference between a £300 GPU and the £150 version of the same family is just "disabled shaders" or such, as the hardware can be the same. Very much a hit or miss really.
Obviously people who enable the 8th SPE won't be able to do much with it while playing released games, as these have been coded for a PS3 with 7 SPEs.

 

[_xxx_]

So you're not sure then too are you? You just confirmed the topic creator's speculation with your speculation --> it is possible...

It is not. When you sell a device, you have to certify it on many levels with specs firmly set in stone. So from the legal POV alone, it's not possible and they won't do it. Maybe they could do another version of the console, but it would definitely have to be declared as a different device.

 

[StefanS]

The 8th SPE should be regarded as not there.

I was wondering, if Sony could save money by physically removing the eight SPE from the chip, once the yields are really good or if that redesign would be too problematic / expensive.

 

[London Geezer]

I was wondering, if Sony could save money by physically removing the eight SPE from the chip, once the yields are really good or if that redesign would be too problematic / expensive.

I think that the symmetry of the SPE array would mean that you have a hole in the chip... If Sony find a way to make the Cell with 7 SPEs straight away in an affordable way, they will surely do it in one of their shrinking processes.

Heck they could put a EE+GS in there!

 

[Guden Oden]

I was wondering, if Sony could save money by physically removing the eight SPE from the chip, once the yields are really good or if that redesign would be too problematic / expensive.

Then you just removed your redundancy, and eliminated the reason for your good yields.

Seriously, I don't think chip defects are ever going to be eliminated... It's one of them facts of life. Since the SPU array takes up such a large space of the die (60+ percent), if you can disable one, ANY one of them, then that likely does a lot for the bottom line. Besides, I don't know how they would lay out 7 SPUs and connect them with the EIB in a way that would actually save space compared to a full 8 sitting in a straight line... It doesn't seem feasible to me.

 

[Shifty Geezer]

By 2011 no doubt Sony could enable 8 SPEs on nearly every Cell they fab, but that's not what rules this out as impossible. What rules it out is that all future PS3 software will need to be able to run on all iterations of the hardware, and this is why as far as PS3 is concerned, that single SPE will always be masked off.

Technically speaking, for games this is an impossiblity due to compatibility, but for Linux, would there need to be a software cap to 8 SPEs? If you had a program that could determine the available SPEs and distribute processing across them, you could stretch to an 8th SPE. That might be something Sony would consider for distributed processing if they get their networked PlayStation supercomputer scheme off the ground. If including an extra SPE has no negative impact (games would just not use it) then why not enable access to it?

 

[Crossbar]

Then you just removed your redundancy, and eliminated the reason for your good yields.

Seriously, I don't think chip defects are ever going to be eliminated... It's one of them facts of life. Since the SPU array takes up such a large space of the die (60+ percent), if you can disable one, ANY one of them, then that likely does a lot for the bottom line. Besides, I don't know how they would lay out 7 SPUs and connect them with the EIB in a way that would actually save space compared to a full 8 sitting in a straight line... It doesn't seem feasible to me.

There are probably more redundant parts in the Cell beside SPEs, remember the DD3 revision due to yield reasons?
To cut down to a 7 SPEs layout, probably isn't that hard when you moved down to 40 nm as there probably are parts of the PPE that can be reshuffled as well.

What might keep them from cutting down to a 7 SPE layout as I see it, is the case that the Cell goes main stream in other consumer devices in large scale, then there may be some economies of scale that kicks in where a large part of the 8 working SPEs Cells go into those devices and the flawed (7 working SPEs) goes into the PS3s. For this to happen XDR-ram also has to go main stream, I wonder if that will happen?

 

[Ragnarok]

I was wondering, if Sony could save money by physically removing the eight SPE from the chip, once the yields are really good or if that redesign would be too problematic / expensive.

Not an option because it's not always the same SPE that's inactive. It's whichever SPE comes out of the fab line with impurities on the die. It keeps Sony from having to throw away all the chips that come of the line with only 7/8 clean SPE's.

 

[Platon]

From the title i got the 8th wonder of the world kinda of vibe...

 

[Johnny Awesome]

Is this really a valid thread?

 

[rounin]

Is this really a valid thread?

At first no, but Shifty brought in a good point about unlocking the 8th SPE for future Linux use. It would be viable I suppose, if later on, SONY releases a patch/update that allows ppl to unlock it for Linux usage if the 8th core passes a stress test or something similar.

 

[Shifty Geezer]

It might not even need a patch to unlock it. If we assume there's a Game mode and an OS mode, the Game mode would limit the Cell use to 7 SPEs, but the Linux mode could be open. This'd be wanted if Sony were to allow their idea of sharing Cell's over the network. Ideally, according to their ideas, you could get two PS3's and network them together, and have the Cell's cooperate. The distributed computing model using the SPUlets or whatever the code snippets were called, and a scheduling system, ought to be able to poll all available SPEs on the system and allocate activities. In which case, locking out a local SPE makes no sense.

In the context of gaming the 8th SPE is irrelevant, but it's certainly something that might come into play in other functions. I see no technical or other reason to limit Linux applications to 7 SPEs.

 

[acaeus]

what if the a SPE fails?

(OT) A curiosity of mine: what if out of the 7 working SPEs one fails, so that the PS3 has only 6 working SPEs? Will it die? Will it complain and lose perfomance? Will it not complain and lose performance?

maybe it has been explained before....

 

[Kryton]

(OT) A curiosity of mine: what if out of the 7 working SPEs one fails, so that the PS3 has only 6 working SPEs? Will it die? Will it complain and lose perfomance? Will it not complain and lose performance?

maybe it has been explained before....

Extremely unlikely! The reason there are 8 SPEs is for defects in the manufacturing process, if any SPE fails standard manufacturing benchmarks they can simply 'lock it out' (burn a fuse) of the EIB and the rest of the chip will function as normal. Once these tests have been done in the fab there should be no reason why an SPE would fail, just like there is no reason your AMD/Intel processor doesn't fail.

 

[slider]

acaeus, do you mean the 7th SPE "failing" on production - i.e. outta the fab? Or do you mean once the Cell is already inside an assembled PS3?

Anyway, outta the fab: It'll be put aside for some other use. Failure in situ: Find your warranty!

 

[swaaye]

Well the only time I've seen people able to enable parts of a CPU that are disabled is with some AMD CPUs for cache RAM. And to do that you had to modify the chip package (connect bridges, etc). Something tells me this isn't going to be a simple software disable. Doing it in hardware would seem more reliable to me. I'd also think that they'd use a more modern approach without bridges, like Intel does and has been doing since P2 with blown internal fuses.

 

[acaeus]

To Slider: yes i was refering to production, once a gamer is using the system and one of the SPEs die. I assume the ps3 will not start and will indicate some error. The worst possibility would be to silently keep on wroking with a drop in performance (cause of the missing SPE).

Extremely unlikely! The reason there are 8 SPEs is for defects in the manufacturing process, if any SPE fails standard manufacturing benchmarks they can simply 'lock it out' (burn a fuse) of the EIB and the rest of the chip will function as normal. Once these tests have been done in the fab there should be no reason why an SPE would fail, just like there is no reason your AMD/Intel processor doesn't fail.

There are many external influences that can cause a cpu to fail. There is also a possibility that even though components passed the lab test they aren't perfect and normal wear and tear will break them, eventaully.
I agree it's unlikely though, assuming the manufacturing process and testing are done well.

 

[Kryton]

To Slider: yes i was refering to production, once a gamer is using the system and one of the SPEs die. I assume the ps3 will not start and will indicate some error. The worst possibility would be to silently keep on wroking with a drop in performance (cause of the missing SPE).



There are many external influences that can cause a cpu to fail. There is also a possibility that even though components passed the lab test they aren't perfect and normal wear and tear will break them, eventaully.
I agree it's unlikely though, assuming the manufacturing process and testing are done well.

Are you just trying to troll? There is no reason why a CPU should fail like that; look at the PC world, servers are on 24/7 without 'breaking' because their CPU mystically fails due to a solar flare on Sirius A. The Cell is just another CPU, same as every other CPU on the planet - they don't generally break once they've been tested in the plant unless you do something stupid to them (putting the wrong voltage through, incorrectly seating them, ...).

Edit: If they do add another SPE I'd expect features like the PSX to be included so, although un-accessible to games (they simply won't have code for it), it will handle additional tasks like video compression for a DVR etc. It would be suicide to add one with no ability for other customers to upgrade (see MS and HD-DVD, feature crippled game wise but will probably be merged into the main-line product rather than an accessory within a year).

 

[Shifty Geezer]

Something tells me this isn't going to be a simple software disable. Doing it in hardware would seem more reliable to me. I'd also think that they'd use a more modern approach without bridges, like Intel does and has been doing since P2 with blown internal fuses.

Is that likely? Would Sony deliberately break a SPE in a 1:8 Cell once they start using them because yields are improved?

I guess that might happen. I'm think of the Sapphire Radeon 9600 (or was it 9500?) here that had some bits disabled, and a hack enabled them and you got a 9700 or whatever pretty much but without the premium. Would anyone who's producing fully working chips deliberately knobble part of those chips in hardware to make a lesser component? Especially in the case of Cell in the PS3 where you haven't got low and high end markets for what's essentially the same product.

 

[acaeus]

Are you just trying to troll? There is no reason why a CPU should fail like that; look at the PC world, servers are on 24/7 without 'breaking' because their CPU mystically fails due to a solar flare on Sirius A. The Cell is just another CPU, same as every other CPU on the planet - they don't generally break once they've been tested in the plant unless you do something stupid to them (putting the wrong voltage through, incorrectly seating them, ...).

Edit: If they do add another SPE I'd expect features like the PSX to be included so, although un-accessible to games (they simply won't have code for it), it will handle additional tasks like video compression for a DVR etc. It would be suicide to add one with no ability for other customers to upgrade (see MS and HD-DVD, feature crippled game wise but will probably be merged into the main-line product rather than an accessory within a year).

So let's say the heatsink wasn't that well attached to the cpu and after shipping if moved just enough so head dissipation isn't proper/enough anymore... Or the fan attached to the heatsink fails (for any reason)... Or you drop the box and a pieace of xxx punctures the cpu....

BTW, the second case - fan failing (got entangled in some cables) and CPU overheating actually happened to my AMD64.