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On Thursday, September 10, 2015 12:20:39 PM james wrote: |
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> You are taking a very conservative view of things. Codes being worked |
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> out now for clusters, will find their way to expand the use of the |
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> video card resources, for general purpose things. Most of this will |
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> occur as compiler enhancements, not rewriting by hand or modifying |
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> algorithmic designs of existing codes. Granted they are going to |
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> mostly apply to multi-threaded application codes. |
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Your being over-optimistic. It seems to me all they're hoping for is to define |
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a standardized and portable high-level interface for programming accelerators. |
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The ones that will benefit the most is the same applications that can benefit |
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from lower level technologies like CUDA. Scientific/number crunching |
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applications, some kinds of clustering, etc. |
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With no synchronization most existing multithreaded designs cannot benefit from |
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it. And obviously code running on the accelerator cannot branch into the CPU, |
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so no system or library calls. That leaves only purely number crunching loops. |
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There's little of that on desktop and few of them can be fully optimized for |
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parallelization. And to be worth the overhead of offloading the CPU needs to be |
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maxed out. That leaves only the few applications I mentioned before. |
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I'm looking at Intel MICs[1] and those look a lot more promising though still |
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of limited use for desktops. It uses OpenMP so it has a lot less restrictions |
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than OpenACC (a few ebuilds in the tree can already benefit from it with minor |
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patches) and you can even offload whole proccesses. You can even ssh to the MIC |
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since it runs Linux. It's not for the average desktop but they're not too |
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expensive either. It may be worth it for high-end gentoo workstation (you can |
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offload compile jobs with distcc) and I got a project on the backburner that can |
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benefit from it. |
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Do you know of any plans to enable offloading on the gentoo toolchain? I was |
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able to build the offloading compiler using crossdev with a few hacks and wrote |
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an ebuild for Intel's simulator[2]. I will work on enabling the host compiler |
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tomorrow and may open a feature request and post patches once I get it |
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working. The changes needed to enable it on the host are pretty trivial. |
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[1] https://software.intel.com/en-us/articles/intel-xeon-phi-coprocessor-codename-knights-corner |
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Fernando Rodriguez |
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