• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
Hannesnisula

Text file I/O - read line functions and buffering

3 posts in this topic

Hi!

 

I'm looking into file I/O for text files and I've been wondering about functions which read lines from files. Does anyone know if they normally read in every iteration (for each character) or read into a buffer to maybe speed things up?

 

I'm developing for Windows and I know the OS buffer readings from files (although one can specify not to, with a flag). Because of this I imagine that reading a single character from a file (the cache, really) in every iteration wouldn't be all too bad compared to buffering the file data yourself, right? Has anyone delved into this or perhaps even benchmarked it?

0

Share this post


Link to post
Share on other sites

This depends on what underlying systems you are using.  In general, this does not matter for disk io though since, as you say, even if you use unbuffered IO the disk IO still reads a disk block at a time and as such ends up with a small buffer preventing repeatedly hitting the disk.  Having said that though, the overhead of the function calls adds up quickly, especially when they talk to OS buffers due to a lot of additional checks that the OS has to perform which you can avoid if you buffer yourself.

 

I did do a test on this at one time.  Using a simple fread 1 character at a time versus simply reading the entire file and then parsing myself, the result was about a 1:5 ratio in favor of the manual parsing.  On the other hand, when I used C++ ifstream and the generic read line function, it turned out to be as fast as the full file version which suggests the C++ streams are pretty smart about behind the scenes buffering.

 

All said and done, I know that the calls to the underlying io functions are generally fairly slow so you want to avoid that.  Other solutions though, you just have to test them yourself.  It should also be noted that I ran this test several years ago on WinXP, it could easily be completely out of date by this time.  So, test test test.. :)

2

Share this post


Link to post
Share on other sites

I have doubts this concern is meaningful. While loading data from disk is necessary and might be performance-critical in some situations, I strongly suggest to keep away from it for all serious use only good reason being memory management.

0

Share this post


Link to post
Share on other sites

This depends on what underlying systems you are using.  In general, this does not matter for disk io though since, as you say, even if you use unbuffered IO the disk IO still reads a disk block at a time and as such ends up with a small buffer preventing repeatedly hitting the disk.  Having said that though, the overhead of the function calls adds up quickly, especially when they talk to OS buffers due to a lot of additional checks that the OS has to perform which you can avoid if you buffer yourself.

 

I did do a test on this at one time.  Using a simple fread 1 character at a time versus simply reading the entire file and then parsing myself, the result was about a 1:5 ratio in favor of the manual parsing.  On the other hand, when I used C++ ifstream and the generic read line function, it turned out to be as fast as the full file version which suggests the C++ streams are pretty smart about behind the scenes buffering.

 

All said and done, I know that the calls to the underlying io functions are generally fairly slow so you want to avoid that.  Other solutions though, you just have to test them yourself.  It should also be noted that I ran this test several years ago on WinXP, it could easily be completely out of date by this time.  So, test test test.. smile.png

 

Thanks for the great answer!

 

I have doubts this concern is meaningful. While loading data from disk is necessary and might be performance-critical in some situations, I strongly suggest to keep away from it for all serious use only good reason being memory management.

 

It's more curiosity than concern, really. I don't think any way would actually impact performance noticeably in my case.

0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0