ReadFileAccel

Read File Acceleration is a hobby project to measure and experiment with new methods to read data into memory from a disk faster.

The experiments are performed on an existing program that has to read a lot of data. A good example program is a game. A modern game needs to read gigabytes of data in a very short amount of time; like, interactive rates are between 16 milliseconds and 33 milliseconds per-frame; 60 and 30 frames per-second respectively.

This work is a bottom-up approach where a system function (like, ReadFile) in another process is replaced with a hook function. The hook functions written so far include:

• A function (ReadFileTrace) to measure how long in microseconds a read took to complete,
• A function (ReadFileCache) to write frequently read data into an in-memory cache,
• A function (ReadFileDirectStorage) to batch reads into a single request, and
• A function (ReadFileDecompress) to read compressed data.

Analysis

There is a python script to analyze read file performance. The script can plot graphs and calculate simple metrics.

Log File Format

A log file (xxxyyyzzz.txt) is written next to the Injector exe file. The log messages are written to a log file in this format:

"ThreadId", "Time", "Event", "Path", "Position (bytes)", "Size (bytes)", "Elapsed Time (microseconds)", ...

Todo

A list of items to work on next:

• Investigate quartiles to more easily compare distribution plots
• Investigate creating a D3D12 device in Injector and passing to hook library
• Investigate hooking into the function to create a D3D device (Alt.)
• Investigate replacing hook library with Microsoft’s Detours
• Create a —no-input mode and a —process-id argument for Injector
• Create a script to start a target process ,get its process id and then run Injector.
• Create a crash hook function to test writing a crash log.
• Creat a prediction hook function to predict reads into the future and have data loaded ahead of time.
• Create a hook router to route to a different hook function by file path rules.
• Create a program to replay read file events.
• Create event structure and function a log event function.
• Create a web server for real-time analysis

DLL Injector

Use this code to inject a DLL into a process.

Enter process-id (pid) to the program and the DLL will be injected!

Set the DLL path by changing the the define DLL_PATH in main.c in the injector folder.

A simple DLL that opens a MessageBox is also attached to illustrate the injection.

Read more at Wikipedia.

Example

$ Injector.exe
Enter pid: 24516
Got LoadLibraryA's address: 00007FF9522A04F0
Wrote path "C://Projects/C/DLLInjector/MyDLL/MyDLL.dll" successfully to address 000001F61B8E0000
Created thread with handle 0000000000000088
Successfuly injected the DLL into the process!