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Everyone in this thread keeps railing on its floating point perf, which is about on par with parts like nVidia's Tesla and similarly priced... but its integer p
by awalton 12y ago
Everyone in this thread keeps railing on its floating point perf, which is about on par with parts like nVidia's Tesla and similarly priced... but its integer performance is why people are really buying these cards up. All GPUs are floating point monsters but integer pansies because that's what their graphics workload heritage turned them into. Xeon Phi is a Computing Monster, with crazy Integer and Floating Point perf, because its heritage was "Let's try to make a graphics card out of CPUs" and not visa versa. It's similar to buying a whole stack of x86 chips just to get to the SSE/AVX units. Only, now you don't need a whole stack of computers, you need a handful of host computers and a stack of add-on cards.
And if you think $2000 is expensive for 60 x86 cores (~$35/core) when all you care about is the SSE/AVX unit and how many vector ops you can cram through it, you're definitely not Intel's target.
- nkurz 12y agoThanks, you are right that I shouldn't have focussed on just floating point. I emphasized it because it better matched the frequently quoted "teraflop in a single card" measurement. As you say, the Phi is equally strong at vector integer operations as floating point, in both cases operating on 512-bit vectors. But I'll quibble with the assertion that all GPU's are "integer pansies", although it's a fantastic phrase. Historically, NVidia GPU's are much stronger at floating point operations than integer because of their graphics origins, and NVidia's Tesla is definitely what Intel views as nearest to the Phi's target market. But AMD/ATI cards have excellent vector integer performance, several times that of NVidia/Tesla, and much better per dollar than Phi until this recent price drop. This is why AMD cards were the best choice for bitcoin mining until the recent arrival of dedicated ASIC's: http://www.extremetech.com/computing/153467-amd-destroys-nvidia-bitcoin-mining http://www.extremetech.com/computing/153467-amd-destroys-nvi...
- DrJosiah 12y agoAs per another post above: > It doesn't support CMOV, MMX, SSE, AVX, and all other ISA extensions the popped up after the original Pentium. I'm not saying it's not useful, it's just not quite as useful as having 60 cores that can just run MMX/SSE/AVX.
- DrJosiah 12y agoAs per another post above: > It doesn't support CMOV, MMX, SSE, AVX, and all other ISA extensions the popped up after the original Pentium. I'm not saying it's not useful, it's just not quite as useful as having 60 cores that can just run MMX/SSE/AVX.