Units for output in acl_quartus_report.txt

When building a set of OpenCL kernels for a FPGA device, aocl produces some info about the logic utilization in the file acl_quartus.txt which looks as follows:

(I built for the SocratesII board with a Cyclone V FPGA)

--- Quote Start ---

ALUTs: 27730

Registers: 53,822

Logic utilization: 25,166 / 41,910 ( 60 % )

I/O pins: 125 / 342 ( 37 % )

DSP blocks: 0 / 112 ( 0 % )

Memory bits: 248,280 / 5,662,720 ( 4 % )

RAM blocks: 230 / 553 ( 42 % )

Actual clock freq: 112.579999864

Kernel fmax: 112.58

1x clock fmax: 112.58

2x clock fmax: 10000

Highest non-global fanout: 4233

--- Quote End ---

I have a vague Idea what they may mean, but since I come from a software (not hardware) background, some of it is a bit confusing, especially as no units are given.

• ALUTs and Registers seem obvious, although I'm not sure if one register holds one or multiple bits.

• I assume the clock frequency is in MHz, but it would seem a bit much for "2x clock fmax" whatever that may be.

• What is the unit for logic utilization? I'm using 25,166 / 41,910 of what exactly?

Supposedly this System has 110000 Logic elements.