Parallella Community

Hi.

I have a small question related Running NET FPGA VHDL Web APPs
http://www.es.ele.tue.nl/mamps/web_serv ... appendices

on the Parallella FPGA Board with the Goal to reduce Power Consumption and at the same Time increase Speed Execution and Efficiency by replacing avarage Server Hardware.

My Idea is to port my C/PHP Written Web Application to FPGA and running it direct from the Hardware
as a Logic instead using any Processors for it.

The DNS, HTTP Webserver services should be run as Hardware Logic too from the FPGA to avoid using any Processor.

My Question is can this be done with the Parallella Board and if yes what
Benchmark Values can be expected compared to a standard Webserver Hardware?

Will it be much faster and less Power consuming then the Webserver Hardware?
Can the Parallella Board be turned/flashed into a specific FPGA Internet Server APP?

It would be great if the Parallella FPGA Board can be used to turn Web Application
written in C or PHP into a NET FPAG hardware specific Application to reduce Power Consumption and increase at the same time Speed Execution of the Task.

Thanks in advance for the Replys.
Greetings LinuXperia.

all the questions you have are all dependant on the implementation in both C/PHP and VHDL. your question is a bit like asking "how fast will the car i'm going to design go and how does that compare to a car i already made?" it's just completely impossible to answer.

the only way to know without actually just timing it would be to add up the number of CPU cycles that occur to execute a specific operation and divide it by the clockspeed of the CPU then look at the gate design generated by your VHDL and calculate the speed based on how many gates are required for a specific operation and then divide that by the speed of the fpga.

a much better (and faster) way to test would be to add some code (to both C/PHP and VHDL) to record the time before and after a specific operation.

as for if it can be done, it depends on how many gates you use for your web application. it could be feasible or absurd, all based upon what you are doing.

i'm just going to take a stab in the dark and say that you havent done anything with VHDL and or low level programming because it's a pretty ridiculous question. if you want to get into digital logic, that's cool but i suggest starting with simple things first.

Hi LinuXperia,

I had a look at that link. They are implementing a soft CPU (Microblaze) to run the actual software stack that is serving pages.

Most soft CPUs I've played with are about equivalent to a 80386SX or 80486SX (32 bit, 100MHz, virtual memory (if you are lucky), no floating point, and so on), and use more power than an approximately equivalent ARM core (as they are implemented in the FPGA's "cells acting as logic gates" not "optimally implemented true logic gates").

Given that you have two ARM cores sitting on the same die I don't think using a soft CPU is of any benefit for either speed or power.

However one time you might want to add a soft CPU core is if you are performing any latency critical functions - For example the ARM cores can do the command and control (and web serving) while the soft CPU handles the realtime DSP processing of audio streams.

Or maybe for robotics - the FPGA can handle the signalling for driving servos and low-level image capture, the Epiphany can perform the image processing/filtering, while the ARMs perform higher level control,

PS. @Gravis, that was maybe a little bit harsh, It also completely ignores the fact the current FPGA designs on the latest silicon is pretty much dominated by routing delays, which you can't really predict in advance... well, other than saying "take your deepest logic, multiply it by the CLB delay, then multiply that by a guessed fudge factor of anything from 1.5 to 3.0, to allow for routing delays".

I think it's also worth pointing out that while implementing a CPU in FPGA for web serving etc. doesn't really make sense, there are certain web application functions that might benefit from being implemented in custom logic. E.g. XML parsing. Then there is also a whole bunch of high-speed/low latency networking too.

Cheers,

Andrew

Hi LinuXperia,

You can download a hardware (no CPU) web server for Xilinx FPGAs from http://www.webphyfpga.com