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Observer joe306
Observer
195 Views
Registered: ‎12-07-2018

Math Execution Times: DSP Processor vs. Embedded ARM Processor

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Hello, many of today's high-end DSP's can do single cycle math and have specialized ALUs. Does the embedded ARMs found on Xilinx FPGAs also have dedicated math structures?

 

Thank you,

Joe
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1 Solution

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Voyager
Voyager
147 Views
Registered: ‎02-01-2013

Re: Math Execution Times: DSP Processor vs. Embedded ARM Processor

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The RPUs contain an ALU, but it's not very powerful and it's there only to give the RPU an edge in completing real-time tasks. See: http://infocenter.arm.com/help/topic/com.arm.doc.ddi0460c/DDI0460C_cortexr5_trm.pdf

The APUs do not have an ALU. They're not really there to do any heavy lifting. They're more like sheperds, or orchestra conductors, making sure data moves around smoothly so the real work can get done by more-apt resources--like IPs and DSPs in the PL, or the GPU, or the VCU, etc.

-Joe G.

HW Guy (can you tell?)

 

7 Replies
Voyager
Voyager
148 Views
Registered: ‎02-01-2013

Re: Math Execution Times: DSP Processor vs. Embedded ARM Processor

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The RPUs contain an ALU, but it's not very powerful and it's there only to give the RPU an edge in completing real-time tasks. See: http://infocenter.arm.com/help/topic/com.arm.doc.ddi0460c/DDI0460C_cortexr5_trm.pdf

The APUs do not have an ALU. They're not really there to do any heavy lifting. They're more like sheperds, or orchestra conductors, making sure data moves around smoothly so the real work can get done by more-apt resources--like IPs and DSPs in the PL, or the GPU, or the VCU, etc.

-Joe G.

HW Guy (can you tell?)

 

Observer joe306
Observer
143 Views
Registered: ‎12-07-2018

Re: Math Execution Times: DSP Processor vs. Embedded ARM Processor

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Hello, thanks for responding to my message. I assume APU is ARM Processing Unit, RPU is Real-time Processing Unit, is that correct?

 

Joe

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Voyager
Voyager
131 Views
Registered: ‎02-01-2013

Re: Math Execution Times: DSP Processor vs. Embedded ARM Processor

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Close... APU = Application Processing Unit. "The Cortex-A53 processor is a mid-range, low-power processor that implements the ARMv8-A architecture. The Cortex-A53 processor has... four cores, each with an L1 memory system and a single shared L2 cache."

Compare that with the official blurb for the RPU: "The Cortex-R5 processor is a mid-range CPU for use in deeply-embedded, real-time systems. It implements the ARMv7-R architecture, and includes... technology for optimum code density and processing throughput."

-Joe G.

Observer joe306
Observer
125 Views
Registered: ‎12-07-2018

Re: Math Execution Times: DSP Processor vs. Embedded ARM Processor

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Thank you very much. Have a great day!

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Observer joe306
Observer
116 Views
Registered: ‎12-07-2018

Re: Math Execution Times: DSP Processor vs. Embedded ARM Processor

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Quick question for you. So if the APU does not have an ALU, I'm assuming that the math is done in software which would take longer. I need to look into this more.

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Voyager
Voyager
108 Views
Registered: ‎02-01-2013

Re: Math Execution Times: DSP Processor vs. Embedded ARM Processor

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The APU doesn't have an ALU, so it's not going to do fast, fancy dedicated operations that you might expect from an ALU.  But the basic A53 instruction sets contain simple math operations (add, sub, mult)--and each core has an FPU and NEON co-processor to help out.

-Joe G.

 

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Scholar drjohnsmith
Scholar
101 Views
Registered: ‎07-09-2009

Re: Math Execution Times: DSP Processor vs. Embedded ARM Processor

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yes and no...
ARMs are fast RISC processors, efficient.

have look here for example
https://www.quora.com/Can-we-use-an-ARM-core-with-FPU-as-a-digital-signal-processor-DSP

The RISC might supriise you on its effeicence and speed for dsp actions.
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