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I actually find the formulae for peak theoretical performance:

Node performance in GFlops = (CPU speed in GHz) x (number of CPU cores) x (CPU instruction per cycle) x (number of CPUs per node)

CPU Speed and CPU cores are easy. but how can i know the cpu operations per cycle? For example, my qualcomm processor specs are as following:

CPU Clock Speed Up to 1.2 GHz CPU Cores:Quad-core CPU /4x ARM Cortex A7 CPU Bit Architecture:32-bit Can someone please help me with this.

Frankie
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  • You need to look up the number of cycles per instruction in the processor manual. ARM will have published them somewhere for the Cortex A7 chip. – Wolfgang Bangerth Mar 10 '17 at 15:44
  • thx for your reply. do you mean that i can find those information in their processor manual? i try to search ARM Cortex A7 and only find some Instruction per second in wikipedia. the data shows as follows: ARM Cortex-A7 dual precision: 1 DP IPC: one VADD.F64 (VFP) every cycle single precision: 2 SP IPC: one VMLA.F32 (VFP) every cycle. but i don't know what is that mean. – Frankie Mar 11 '17 at 03:19
  • A cycle is a clocktick. There are as many clockticks per second as your processor has GHz. – Wolfgang Bangerth Mar 11 '17 at 04:46
  • now i am completely confused. because both of the product manual and the cpu spes does not tell any information on the instruction per cycle.let me say it like this, if i want to calculate the latest qualcomm snapdragon 835 processor, i can only find the CPU is 2.45GHz, 8 cpu cores on their website and it is Kryo 280 CPU. So How can i find the instruction per cycle regarding to this Kryo 280? i guess you are telling i may find it somewhere for those information cause it is ARM architecture. i will try to search. thanks – Frankie Mar 11 '17 at 10:11
  • hi Wolfgang Bangerth, i am sorry that i just back online, i still have not find it yet, however, same results were found on Wikipedia. Qualcomm Kryo 2 DP IPC: scalar FMA or scalar multiply-add 8 SP IPC: 4-wide NEONv2 FMA or 4-wide NEON multiply-add, what is 2 DP IPC and 8 sp ipc mean. is this data shown as 2 DP IPC or 8 SP IPC just what i am looking for? – Frankie Mar 11 '17 at 15:46
  • actually i want to just make sure those processor's processing speed will no more than 5GFLOPS and make sure the arithmetic logic unit within an access width of 32 bit. so i need to know how to calculate the FLOPS. – Frankie Mar 11 '17 at 15:55
  • I have no idea. All I know is that this information is typically published by the manufacturer, but I wouldn't be able to tell you where, nor how to interpret it. – Wolfgang Bangerth Mar 13 '17 at 03:05
  • ok, i understand and very appreciate. thank you again – Frankie Mar 13 '17 at 06:54

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