Benchmarks for embedded processors

Crack applications engineer Bob Martin was walking by just now and we got to talking about people we both knew from our National Semiconductor days. One name that came up was Markus Levy. Bob told me about EEMBC® — the Embedded Microprocessor Benchmark Consortium.

EEMBC

When I read up on the organization, I was delighted to see that Markus started work on embedded benchmarks when he worked at EDN magazine, where I also worked as an editor for 5 years. Back in 1996, it was clear that the old Dhrystone MIPS benchmark was not really meaningful to embedded systems. So Markus got a bunch of industry companies together and proposed the new benchmarks. They got 12 members right off the bat and got funding to establish real-world benchmarks that would be suitable for phones, tablets, routers and other embedded systems. As their about page explains:

“EEMBC benchmarks are built upon objective, clearly defined, application-based criteria. The EEMBC benchmarks reflect real-world applications and have expanded beyond processor benchmarks, also heavily focusing on benchmarks for smartphones/tablets and browsers (including Android platforms) and networking firewall appliances.”

I was glad to see that not only is Atmel a member, but so is ARM, who invented the cores used in Atmel’s 32-bit SAM line of microprocessors and microcontrollers. When you look at Atmel’s benchmark results, You can see our original 8051 processors get a score of 0.1. An AVR 8-bit MCU like the ATmega644 will get a benchmark score of 0.54. In contrast our ARM-core SAM3 and SAM4 chips will get a benchmark score up to 3.3. When I looked at a competitor’s ARM4 offering, I was delighted to see they ranged from 2.0 to 2.8, significantly slower than Atmel’s ARM4 SAM4 chips.

This is congruent with what I hear in the hallways here at Atmel. We just didn’t slap some counter-timers on an ARM core and release it. We took the time to do it right, adapting and improving the really cool peripheral system from our XMEGA 8-bit micros. I assume these benchmarks are just for raw speed, but the cool thing about Atmel’s peripheral event system is that you can have peripherals interact and do DMA without waking up the CPU core and sucking up a lot of power. Still it’s nice that the benchmark shows us as faster. This might mean you can get some chunk of code to execute faster and then get the micro put to sleep, saving power overall. This can be non-intuitive. If the micro’s compiler has more efficient code creation, you can get way more done with the same amount or less power. I know this is true for AVR 8- and 32-bit processors. The AVR was invented and crafted by hardware engineers that understood the importance of C and computer science in general. Although the entire AVR line did not spring fully-formed from the head of Thor, there were some really crafty Norwegians involved.

While the ARM-core SAM chips run ARM instruction sets, they too are optimized for compiling. After all, AVR showed the world how to do this in 1996. And with Atmel peripheral concepts, the SAM chips are really something. Check out the new SAM D20 Cortex M0+ micro for a nice inexpensive chip that can do a whole lot on minimal power.

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