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Parallella: Low-Cost Linux Multi-Core Computing

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  • #11
    I think there are quite a few graphics and multimedia tasks that will run pretty well on it. so while the raspberrypi is very cool and cheap, but a bit disapointing as a desktop (speaking as a pi owner), the parallella will be as fast as a normal desktop for some things (the ARM cpu is already several times faster than the pi's armv6).

    of course the 16 and 64 core versions are not actual supercomputers by todays standards (i work with 48core opteron machine and would not call that a supercomputer). its a step on the way to 1024 and 4096 core chips. the limit in big supercomputing is power usage. i have seen HPC clusters where 1000s of 3 year old servers are thrown out because its cheaper to replace them a few hundred new machines, than pay for the electricity to run them.

    there are many approaches to how to improve flops/watt. you can assume that standard CPUs will get a bit better every year by them selves, or you can try to come up with a whole new way of doing things. one of these is GPUs where you make huge use of SIMD (single instruction multiple data), which is great when you want to do exactly the same operation to each data value, but hopeless when you don't. another is put lots of full x86 cores on a single die, like intels MIC. epiphany is sort of a halfway, lots of simple but still capable independent cores on a chip. They also think that a network like memory system will be more efficient then a cache hierarchy. its hard to know whos right. time will tell.

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    • #12
      Originally posted by ssam View Post
      of course the 16 and 64 core versions are not actual supercomputers by todays standards (i work with 48core opteron machine and would not call that a supercomputer). its a step on the way to 1024 and 4096 core chips. the limit in big supercomputing is power usage. i have seen HPC clusters where 1000s of 3 year old servers are thrown out because its cheaper to replace them a few hundred new machines, than pay for the electricity to run them.
      Dear sir, may you divulge the location of that particular dumpster?

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      • #13
        Originally posted by YannV View Post
        It is certainly a moving target. I remember Apple marketing some PowerPC computers with the term as well, but likely the best comparison we can bring up is in flops/W to actual current day supercomputers. Those seem to hover about 2.1Gflops/W (and that model is #1 of top500 as well). The Epiphany IV 64-core processor is advertised as 100Gflops (peak) with 2W power consumption (max), placing it at nearly 50Gflops/W; but obviously you need a power supply, memory and so on, so it's more appropriate to check the whole board. That has a quoted typical consumption of 5W, so if we bump that up by 2W, and then factor in a pessimistic 80% efficient power supply, we get 11.4Gflops/W. It's certainly in the ballpark, though you'd need thousands of them to make a true supercomputer. The base model (16 cores) has the same power consumption, so just divide by 4.
        Communication overhead will swallow all the advantages.

        I prefer GPU or Intel MIC, even for personal usage.

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        • #14
          Originally posted by zxy_thf View Post
          Communication overhead will swallow all the advantages.

          I prefer GPU or Intel MIC, even for personal usage.
          It depends on the application. The external links (4, one on each side) each operate at 2GB/s, while internal rates are higher ("64GB/s Network-On-Chip Bisection Bandwidth"). As every processor in the Epiphany has a DMA unit, moving data around may not be all that costly.

          There are mainly three reasons for me to prefer the Parallella: firstly the openness, secondly the cost, and thirdly the low power needs. The architectural differences may come in later. This won't mean the GPU loses its place; but if it succeeds it may lower the price for that MIC eventually.

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          • #15
            For the cost it might be fun to play with. It really ends up depending on how easily it is to port existing code over to run on it. 90gflops does seem kind of low considering there are terraflop boards out there (at dramatically higher cost).

            How well it handles double precision is of most interest to me, but that does push the 1GB ram a bit. Single precision would be more interesting to those wanting to try to leverage this thing as a 3d video accelerator.

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            • #16
              Originally posted by bnolsen View Post
              For the cost it might be fun to play with. It really ends up depending on how easily it is to port existing code over to run on it. 90gflops does seem kind of low considering there are terraflop boards out there (at dramatically higher cost).

              How well it handles double precision is of most interest to me, but that does push the 1GB ram a bit. Single precision would be more interesting to those wanting to try to leverage this thing as a 3d video accelerator.

              NO double precision. Only single precision, and not all operations are performed in hw. (division is not handled)

              What all here miss is application in mobile. Where low power and low cost can bring some benefits. That board will be one of (as this company hope) many devices with that technology.

              I can see it as "addon" or "replacement" for current FPU coprocessors in mobile.

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              • #17
                Guys, don't forget that 16 and 64 cores is only to get started. They plan for ~1.000 cores in two years.

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                • #18
                  Originally posted by Rigaldo View Post
                  Guys, don't forget that 16 and 64 cores is only to get started. They plan for ~1.000 cores in two years.
                  This design would clearly challenge current OS kernels if they want to use a single kernel for 1000 cores.
                  Practical (in theory) solutions are still in labs.

                  Originally posted by YannV View Post
                  It depends on the application. The external links (4, one on each side) each operate at 2GB/s, while internal rates are higher ("64GB/s Network-On-Chip Bisection Bandwidth"). As every processor in the Epiphany has a DMA unit, moving data around may not be all that costly.

                  There are mainly three reasons for me to prefer the Parallella: firstly the openness, secondly the cost, and thirdly the low power needs. The architectural differences may come in later. This won't mean the GPU loses its place; but if it succeeds it may lower the price for that MIC eventually.
                  Sounds feasible, if the application won't need many communications.
                  But I still doubt the price of the switchers for the 2GB/s links, clearly there won't be many consumers of this kind of switchers.

                  Gbps Ethernet switchers are much cheaper, while they are not sufficient for large-scale clusters .

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                  • #19
                    Originally posted by przemoli View Post
                    Anyone tested galium3d on that thing?
                    According to Adapteva board doesn't have GPU.

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                    • #20
                      Originally posted by RussianNeuroMancer View Post
                      According to Adapteva board doesn't have GPU.
                      Why do they use the term GPU then?
                      The Epiphany chips are much smaller high end CPUs and GPUs
                      BTW: They are not that open as they state to be, from the FAQ:
                      Will you open source the Epiphany chips?

                      Not initially, but it may be considered in the future.

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