Modern operating systems* cache all your disk accesses in memory. when you read your data from disk into memory, the operating system keeps a copy of the data in memory in case it's accessed again. There's nothing you can do to free that memory, and you wouldn't want to. Next time you try to read that data from the disk, the OS just pulls it out of memory and your start up is 1,000,000 times faster. If you request more memory than is available in physical memory, the OS will release some of its cached data and give it to you. bottom line is don't use task manager to monitor memory usage.

Case in point. Open up a web browser just after your system is fully booted up. You'll hear lots of hard drive clicking. Then close the web browser and open it again. You'll notice very little disk activity.


While I'm talking about memory management, you also should know that there's a difference between physical and virtual memory. When you allocate 1 gig of memory, You are given virtual memory, but the amount of physical memory available to the system doesn't change. It's not until you access the memory that the OS allocates physical memory for you, and this is done a page at a time*.

to get a true feeling of how your user level application is managing memory, you need a tool that will differentiate between memory currently being used by user-space programs and system memory, as well as distinguish between virtual memory and physical memory. I'll defer to windows people to tell you what tools are currently on the market.


[edit] of course, in this case it looks like there was a user-space error.


* I only know for sure how linux handles memory management. I only project that windows would use similar techniques.

Good to hear you got this resolved dbh.

kdogg brings up a very good point, but I would not expect the memory that is being used by the OS for IO caching to show up on your memory profiles.

There are multiple ways to do memory profiling, and there are tools out there that could help you.

In your case I believe that using the debug runtime for DirectX and setting the output level to the max would have given you information about the leak on application exit with the debugger attached.

If I remember correctly WIN32 has functions for getting information about the memory used in your process. There are also C-runtime functions that would help you track memory leaks down (Look for _CrtSetXXXX in MSDN)

Some commercial tools like BoundsChecker could help you as well, but such tools are expensive and target a production setting. You can download the trial version to try it out.

Kinda curious myself, what would be a better way to check how much memory your application is using instead of ctrl-alt-del window?