On Tue, Oct 16, 2012 at 9:31 AM, Jari Kirma <[email protected]> wrote: > Although I'm fan of Parallela, just a small comment on GPUs vs. Parallela: > although both are computing technologies exploiting parallelism, they are > also quite different beasts. GPUs tend to be vectorized, often leaning > towards VLIW architecture and have considerable amount of > application-specific units and instructions.
yes. this is why i particularly like ICubeCorp's approach. they've ported open64 to their architecture, which is a VLIW multi-core general purpose processor with instructions that help accelerate both video and 3D graphics. rather than have a separate GPU with its own built-in CPU. or a video engine with its own built-in CPU. i've dealt with things like the Aspex Semiconductor's "ASP". parallel processors like this: i tell you, they're absolute hell to program. when i say "hell" i mean that you can measure the number of lines of assembly code in *days* per line of code. not lines of code per day - DAYS per line of code. the benefit however is that for certain algorithms you get a performance boost of 10:1 or even 100:1 over any other type of chip (on a price-performance metric). in the case of the parallela IC, the grid arrangement is something that, with a hell of a lot of work, could be exploited to say dedicate 16 of the 64 cores to performing 3D GPU SIMD (vector) processing. another 16 could be dedicated to video processing, and so on. but it would take an enormous amount of work to do that hard-coded programming. where are the tools which aid and assist in doing that, and take away much of the pain? by contrast, ICubeCorp's processor, because they have a compiler expert on board with over 15 years of experience with SGI *before* he started work for ICubeCorp, you can just take the standard free software MesaGL library for example, and do "CC=/usr/bin/mvpcc ./configure" and err... you're done. when you have a decent compiler that takes care of all the hard work, the advantage of the VLIW approach is that the clock speed is *much* lower yet achieving performance that rivals systems with 3 or 4 times the clock rate (and therefore roughly 10 to 15 times the power consumption). tensilica is another company that has a VLIW compiler associated with their RISC core. both are unfortunately proprietary: the performance however is unrivaled, and they've sold over 1.5 *billion* RISC core licenses, world-wide. whereas, the work that ICubeCorp has done on porting open64 to their architecture is, of course, entirely GPL'd. the bottom line is that whilst i'm delighted to see what parallela are doing, they're still quite a long way behind, in actually getting anything useful from a commercial perspective out the door. their architecture is very similar to what ziilabs have, *BUT*, remember: ziilabs grid-based parallel processor is on-board in combination with an ARM processor (ZMS08 etc.) what i'm trying to say is that whilst parallela's approach is laudable, they've only done about 25% of the work needed (the hardware side). to be a commercial success, they need the software side as well. not just to release the tools or the documentation, which is of course itself a laudable step, but to *prove* that, commercially, they can handle 1080p30 video, and that they can do over 70 million triangles per second or whatever it is. l. -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: http://lists.debian.org/capweedwm7ub8s7g9q6ujpocmregye3ruvsjzae7wvxrfbjr...@mail.gmail.com
