FlashDriver

A User-space Flash Simulation Platform.

Architecture

  --------------------------------
  |          Interface           | e.g. local, network
  --------------------------------
                 |
  --------------------------------
  |          Algorithm           | e.g. PFTL, DFTL,  etc.
  --------------------------------
                 |
  --------------------------------
  |            Lower             | e.g. BDBM, POSIX(file), memory(RAM Drive), etc.
  --------------------------------
  
/*
 * Each layer is bundled to dedicated directory, - interface/ algorithm/ lower/ -
 * and implemented components of layers would be mapped on Makefile (expain it on the bottom)
 */

1. Interface

The first layer handles user requests with LPA, which means it works like block layer of kernel.
We provide a simple micro-benchmark program on interface/main.c.

However, to test with user application such as FIO, you must forward block-level requests to this layer.
We currently use NBD kernel module to test performance of our platform. (add details later)

2. Algorithm

This layer is designed to simulate FTL in SSD.
It translates LPA(from interface) to PPA(to lower) using their own mapping algorithm of each module.
Various LPA to PPA mapping algorithms could be implemented on top of it.
You can easily create your own FTL module with FlashDriver's form.
(Refer algorithm/normal/ for example)

3. Lower

Lower layer is a mimic of physical addressing part of SSD.
This layer forwards requests, which consists given PPA from upper layer, to selected lower module(e.g. BDBM, POSIX(file), memory(RAM Drive)).
For example, to simulate with posix systemcall, it would call posix APIs to read/write to given address. (read(), write(), lseek())
To implement new lower module, the target platform have to expose essential interfaces to read/write actual data.

How to run

Setting

FlashDriver$ vim ./include/settings.h
-> set GIGAUNIT variable as device size (e.g. #define GIGAUNIT 32L for 32GB test)

FlashDriver$ vim ./interface/main.c
-> add benchmarks what you want (e.g. bench_add(SEQSET,0,RANGE,RANGE); for sequential write bench)

Make new main file

1. copy ./interface/mainfiles/default_main.c [your_main_file]
2. edit the your main file
3. edit Makefile
original Makefile:131
driver: ./interface/mainfiles/default_main.c libdriver.a
	$(CC) $(CFLAGS) -o $@ $^ $(ARCH) $(LIBS)

edited
driver: [your_main_file] libdriver.a
	$(CC) $(CFLAGS) -o $@ $^ $(ARCH) $(LIBS)

Makefile

FlashDriver$ vim Makefile
-> You can select module for each layer to operate with.

[Example]
TARGET_INF=interface
TARGET_ALGO=dftl            # Demand-based FTL
TARGET_LOWER=posix_memory   # memory(RAM Drive)
-> Make with interface as Interface module
   dftl as Algorithm module
   posix_memory as Lower module

* Directory name of targets must exist on each layer's directory
  (e.g. algorithm/dftl/ lower/posix_memory/ )

Run

FlashDriver$ make driver
FlahsDriver$ ./driver

Help

Contact to junsu_im@dgist.ac.kr or jinwook.bae@dgist.ac.kr
README would be updated someday