File Read/Write Comparison between Win32, CRT, STL and MFC

I have decided to make a comparison for file IO operations on Win32, CRT, STL and MFC.

For all four libraries/APIs I have done the profiling in the following way:

• open the file
• allocate the buffer used for reading
• start the timer
• read/write from/to the file
• stop the timer
• close the file
• release the memory

This way, the profiling only applies on the read or write operations, not on other task such as opening and closing files, allocating or releasing memory.

What I’ve used:

• Win32: functions CreateFile, ReadFile, WriteFile and CloseHandle
• CRT: functions FILE, fopen, fread, fwrite and fclose
• STL: for reading class std::ifstream, and methods, open(), read() and close() and for writing class std::ofstream and methods open(), write() and close()
• MFC: class CFile, and methods Open(), Read(), Write and Close()

I have performed the reading with different buffer sizes: 32, 64, 128, 256, 512 bytes and 1KB, 2KB, 4KB, 8KB, 16KB, 32KB, as well as with a buffer accomodating the entire file. Same buffer sizes were used for writing. For testing the write operation I also wrote the file at once. In all cases, I generated a 16MB file.

To decide which one is better overall, I have associated a score with each result. The faster (for each buffer size) got 4 points, the next 3, 2, and 1. The bigger the sum, the more performant overall.

I have run the program on two files for reading on a Intel(R) Pentium(R) 4 CPU at 3.20GHz, 1 GB RAM, running Windows XP, SP2. The results, representing an average of 15 runs, are shown bellow:

File 1: size 2,131,287 bytes

File 2: size 110,999,662 bytes

The first conclusion is that overall Win32 is the fastest, followed by MFC, then by CRT, the slowest being the STL.

The second conclusion is that CRT is the fastest with buffer sizes smaller than 256 bytes, and then Win32 and MFC are the faster.

The results for writing were a quite similar. Of course, running several times, can produce slight variation in the results (both for read and write).

File 3 : size 16,809,984

You can download the project I used for the benchmark from here.