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IBM did this with the PowerPC chips used in the Playstation 3. It was a development headache but part of that was the low power cores were extremely limited...
by mackman 6y ago
IBM did this with the PowerPC chips used in the Playstation 3. It was a development headache but part of that was the low power cores were extremely limited... no shared memory so you had to DMA data over and double buffer. They ran mighty fast though. It was a lot like programming a DSP really. If this is anything like that I would expect only some workloads to be pushed to the small cores in a similar way to the way stuff is pushed to GPU today. Frameworks will pop up to make it easier for developers but it will be rough at the get-go.
- rbanffy 6y agoThe Cell was very different, and horrendously hard to program. The SPUs had no direct access to memory and had to be fed via DMA transfers coordinated from the PPUs.
- wtallis 6y agoYeah, there was no way to pretend the Cell was anything close to a traditional SMP design. But Intel's Lakefield and Arm's big.LITTLE are very much meant to be treated as SMP systems, with just a few tweaks on top to deal with/take advantage of the fact that they're not completely symmetrical. That means the CPU designers actually have to be more careful about what functional differences they allow to creep in.
- rbanffy 6y agoI'm assuming the difference in supported instructions will have to be very minimal. OSs will need to be careful not to move a process from one core to another that supports a subset of the instruction set it was expecting.
- masklinn 6y ago> IBM did this with the PowerPC chips used in the Playstation 3 It was a completely different situation, the Cell's SPE were vector coprocessors, they were a completely different architecture than the PPE but they were also interacted with explicitly from the PPE.
- sjwright 6y agoHow did Cell compare to doing compute on a GPU? Was the difference in complexity due to support libraries etc, or because it required non-standard thinking about how it can be utilised?
- sjwright 6y agoI remember reading or watching something by Naughty Dog about how they maximised use of Cell which was fascinating. (And something about how they ported to PS4 and made extremely efficient use of the eight cores by running game/physics in parallel with the previous frame’s rendering/graphics. Or something like that. It was ages ago and I can’t seem to find the talk online.)