The Untapped Potential of the PS3’s CELL Processor And How Naughty Dog Tamed The Beast

A look back at what made CELL challenging yet special and how developers like Naughty Dog managed to effectively utilize it.

Posted By | On 16th, Aug. 2017 Under Article, Graphics Analysis


Consoles harware isn’t, well, it just isn’t unique anymore. With the advent of x86-based consoles like the PS4 and Xbox One, the days of wild, custom hardware architectures are long gone. While Microsoft certaintly wasn’t kidding around when it said that the Xbox One X was the most powerful console ever made, at the end of the day, the Xbox One X isn’t all that different from an upper midrange PC, hardware-wise.

This isn’t to say that standardization isn’t without benefits: today’s consoles make life much easier for developers, who can easily build games for multiple platforms with ease, since the underlying hardware is similar. This is a good thing for both console and PC gamers. This generation, more multiplats have made their way over to PC than ever before. Series as wildly disparate as Tekken, Metal Gear Solid, Dynasty Warriors, and Destiny have made their debut on PC this gen thanks both to a growing PC audience and greater ease of cross-platform development.

But this wasn’t always the case. Sony, in particular, has a history of experimenting with custom architectures for consoles. The PS3’s Cell processor in particular is a fascinating case.

ps3 cell processor

"The SPEs were a set of 8 further streamlined processor cores, with limitations such as not feature cache and not having branch prediction. Engaging the PPE was straightforward. The trouble came from getting the SPEs to perform to their fullest extent."

Development on Cell began in 2000, when the PS3 wasn’t much more than a whiteboard drawing. Sony teamed up with Toshiba and IBM in a joint venture (creatively) called STI for a wide range of commercial applications, ranging from scientific work to graphics and physics processing. What’s important to note is that while powerful, Cell wasn’t purpose-built for gaming and this had implications for PS3 game development down the road.

Circa 2005 when the PS3 was announced, the Cell was a radical departure from anything on the market. The very first dual core processors in the world, the Athlon x2 and the Pentium D, were released in May 2005, the same month that the PS3 was announced at E3. In contrast, the PS3’s Cell featured what’s essentially a 1+8 core design, optimized for running parallelized code. The PPE, or PowerPC Processor Element, is at the heart of Cell. The PPE is essentially a rather simplified general purpose processor based on the PowerPC architecture. PowerPC-based hardware was fairly common at the time, with MACs having shipped with PowerPC processors until 2005.

xbox 360

"The Xbox 360 made use of a unified 512 MB RAM pool, shared by both the GPU and the processor. This allowed for a degree of flexibility when it came to, say, budgeting for a higher resolution texture."

So far, we’re basically looking at a single PowerPC core running at 3.2 GHz. So far, nothing special–the Xbox 360’s Xenon processor consists of three of these. The SPEs (Synergistic Processing Elements) are what made Cell unique (and, of course,  what made it uniquely challenging for game developers to work with). The SPEs were a set of 8 further streamlined processor cores, with limitations such as not feature cache and not having branch prediction. Engaging the PPE was straightforward. The trouble came from getting the SPEs to perform to their fullest extent.

The Cell’s wide architecture played a big role in the deficit that was often seen between the PS3 and Xbox 360 in 7th-gen multiplats. Skyrim’s among the worst offenders, but many titles, from Assassin’s Creed to the Far Cry games often ran and performed worse on the PS3. For much of the seventh gen, dual-core processors were common in the PC space and the Xbox 360’s Xenos was tricore. As a result, there was an emphasis on writing code optimized for high single-threaded performance. This was great if you were rocking a Core 2 Duo or an Xbox 360, with its 3 3.2 GHz PowerPC cores. But the same code wouldn’t run so hot on the Cell: you have one, relatively high-performance PPE and 8 specialized SPEs. Oftentimes, developers simply opted to make minimal use of the SPEs, offloading most of the processing load to the single PPE.

uncharted 1 ps3

the last of us ps3

"The potential of Cell is nowhere more evident than in Naughty Dog’s PS3 games. One only needs to take a look at the visual jump from Uncharted 1 to The Last of Us."

This was obviously problematic from a performance viewpoint. Moreover, in the case of game engines that were optimized for single and dual-core performance (such as Skyrim’s Creation Engine), there wasn’t much that could be done apart from this very unoptimal solution. This is the reason behind sub-25 FPS framerates in games like Skyrim with extensive world-building and AI to handle in terms of the CPU load.

While multiplats generally fared poorly on PS3, first-party titles were another matter, offering better visual fidelity and scope than most exclusives on the Xbox 360. A studio like Naughty Dog, with greater experience working with the harder and better accessibility to Sony itself were able to wring the most out of the SPEs over time. Interestingly, Kaz Hirai himself is said to have said that the Cell’s unusual architecture was deliberate–that making the PS3 hard to code for meant that developers would only slowly tap into the PS3’s full potential, allowing titles to keep pushing the limit years after the PS3 came out. The potential of Cell is nowhere more evident than in Naughty Dog’s PS3 games (one only needs to take a look at the visual jump from Uncharted 1 to The Last of Us).

When the Cell was optimized in the best possible manner to deal with the PS3’s GPU, there was a drastic increase in polygons in character models when one compares Nathan Drake from Uncharted 1 to Joel from The Last of Us. Environmental effects look more detailed, higher resolution textures were now being accomodated  (anyone remembers this tree from Uncharted 2?), monumental improvements in NPC interaction (Ellie from from The Last of Us is a great example) and phenomenal improvements in dynamic lighting and physical based rendering (although limited), and all of this at a rather steady frame rate. Credit must also be given to the PS4 Graphics team (the ICE team) for optimizing the PS3’s API in order to streamline communication between the CPU, GPU and memory. In many ways, the optimization implemented during the later days of the PS3 CELL processor set the benchmark for future PS4 development framework and tools.

In Naughty Dog’s own words, “Uncharted 1 used maybe 30 percent efficiency. Uncharted 2 we were finally using 100 percent, but it wasn’t as efficient as it could be. Then, Uncharted 3 we got way more efficient. With The Last of Us, we are as efficient as we can possibly be. It’s just squeezing every last drop of power out of the system.” Going from Drake’s Fortune to Drake’s Deception sees a night-and-day improvement in visual fidelity, made possible by the years Naughty Dog spent familiarizing themselves with the Cell’s quirks. It wasn’t just the wide Cell architecture that made the PS3 a challenge to develop for. The Xbox 360 made use of a unified 512 MB RAM pool, shared by both the GPU and the processor. This allowed for a degree of flexibility when it came to, say, budgeting for a higher resolution texture.

The PS3 on the other hand utilized a split memory design, with 256 MB allocated for the GPU and another 256 MB for the CPU. In addition to the fact that the PS3 versions of multiplats often used lower-resolution textures, they often featured a lower framebuffer resolution as well, in order to avoid going over the tiny 256 MB VRAM budget.

"With the PS4, Sony’s played it smart by rectifying many of the PS3’s shortcomings. A shared 8 GB pool of memory–16 times as much as the PS3 had– is by and large sufficient at 1080p."

Despite the Cell’s quirks, and despite the other teething problems the PS3 faced such as backlash to its exorbitant launch price, the console did surprisingly well for itself. New PS3 unirs continued to be released as late as last year, a full decade after the console launched. That’s a frankly staggering degree of longevity for any kind of electronics hardware. With the PS4, Sony’s played it smart by rectifying many of the PS3’s shortcomings. A shared 8 GB pool of memory–16 times as much as the PS3 had– is by and large sufficient at 1080p. While the Jaguar processor cores are relatively weak compared to their PC counterparts, their shared x86 architecture makes coding for the PS3 a much easier task. And, last but not least, the price was right: For $399 at launch, and now available for $299 and less, the PS4 offered a lot more for a lot less. A sound pricing strategy is a big part of the reason why the PS4 is Sony’s fastest-selling console to date.

But still, with the PS3 on its last legs, it’s nice to look back at what made the last-gen console special and so long-lived, quirks and all.

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  • Mavericks

    You’re forgetting to relembre that Sony initially planned PS3 with two Cells and no GPU, making ONE of the processors tô act like a GPU.

    They failed.

    • DarthDiggler

      @gabegreca:disqus

      They failed.

      The PS3 is #6 in all time console sales, edging out the X360 (which had a year head start) by about a million units.

      What is your definition of failure?

      https://uploads.disquscdn.com/images/ac7300aae7de78c2a4f4251ef5012ebd80fe99ca2e84a50ed1f861cbb5b07b00.png

    • quantum

      Remind us again which part of the article is talking about sales?
      The guy was talking about hardware and in some weird twisted reply you post a picture of a sales chart in answer to his comment.

    • DarthDiggler

      @disqus_HPgYof4iyn:disqus

      Sales are a great metric to judge failure and success so I questioned @gabegreca:disqus’ definition of failure given the success of the PS3 hardware.

      The chart is a very good response. Is the concept of sales being a metric for success over your head?

    • Fweds

      Sony released a Cheap junk PS3 console to boost sales towards the end it was rubbish, I’m talking about the one that had most of its features dropped and had that terrible manual eject Blu-ray drive.

    • DarthDiggler

      @Fwedds:disqus

      Sony released a Cheap junk PS3 console to boost sales towards the end it was rubbish, I’m talking about the one that had most of its features dropped and had that terrible manual eject Blu-ray drive.

      Rubbish? According to who? Not according to the millions of people who bought the PS3 and generated a demand that allowed Sony to win the last console sales contest. Which MS was winning with an entire year head start.

      Do you really think people late to the PS3 really cared about the eject button when they were playing The Last of Us? I highly doubt people were mad they couldn’t load Linux on their PS3s when they were playing Uncharted 2. Sony did trim a few features, but they delivered great games in their place. Sony always delivers great games because they nurture talent. MS for the most part just tosses money at studios, the difference in strategies shows in the games, especially the TRUE exclusives.

      I get it you don’t like Sony or PlayStation, that is fine you don’t have to like them. Suggesting that Sony used a bad strategy to deliver an economically viable console which lead to their success in the last generation is just silly talk.

      Please don’t get all SJ777 or 7770777 on me. No one wants to be that guy.

    • Eddie Battikha

      Ya it sure was Confusing.

  • stopbeingafanboy

    Because…Naughty Gods.

  • Wei Feng

    xbox one’s second GPU

  • Wei Feng

    is

  • Mark

    Great article that takes me back to memory lane Arjun. Although the 360 had better multiplats, even I could see Uncharted and Last of Us was graphically the best out!

    • DarthDiggler

      @Dupree82:disqus

      Although the 360 had better multiplats,

      PS3 started to get parity with 360 in terms of third party games and some games actually exceeded the 360 on PS3 in terms of graphical prowess. It was usually in the form of better effects or anti-aliasing.

    • Mark

      Well yeah, but let’s just give the 360 the W in that category. Both systems were GREAT for what they brought to the table!

  • Billy

    Just to be clear every system has more potential than what it is ran at, with the exception being those of us who have PCs and optimize them ourselves; and I am not just talking about overclocking. When console devs say customized mostly they mean governed down, sometimes to prevent bottle-necking so there almost is always more power more potential when consoles are first released. Now as to how it can be tamed, if you have years so many in fact that the console is almost obsolete to study, make compare driver updates those that work and down then yes you can open some potential up though it makes little difference once the console is about 5 to 6 years in. I play every system yes I have a favorite but when I look at which I play which games on I go by who I want to play that game with, friends on which system, I rarely buy double games. I do look at the hardware and how the console dev utilizes it, I do not get caught up in who will out do who in sells or power. Truth be told each system could out do the other if they know what the other is doing, sometimes I wish they would hold the specs to some existent until the day they are prepared to put them out for preorder. As for 1st party games it changes year to year so what-ever. I love PS Xbox PC, even Nintendo they all have their pros and cons if your just looking for one thing then go after that one thing and be blind to, well everything but if your willing to see your systems defects then you can demand they make it better. For instance most gamers think that the Gddr3 ram is bad and yes it is but it is the eSRam that made the Xbox One faster by GB per seconds that made it so hard to work with, eSRam is great for boosting systems but it works best to boost an already stable system and works poorly when it is used to stabilize that system, and now Xbox has opted not to use eSRam on the XBOX (Xbox One X) the best reason is not that it did not work but it did not work well and it was difficult to optimize games with, unlike conventional ram; though I would of used it with the 12gb of gddr5 ram to help with more taxing games even a small amount would of helped allot. I could go on but why and I could go though each console the same way but why, each of us needs to do it for ourselves and stop being told which is best because the truth of the matter is “best” is subjective to each gamer and what their expectations and abilities are.

  • Mr Xrat

    lol Xgimps are still mad at the PS3’s comeback.


 

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