Clear file cache to repeat performance testing

A command line utility can be found here

from source:

EmptyStandbyList.exe is a command line tool for Windows (Vista and above) that can empty:

• process working sets,
• the modified page list,
• the standby lists (priorities 0 to 7), or
• the priority 0 standby list only.

Usage:

EmptyStandbyList.exe workingsets|modifiedpagelist|standbylist|priority0standbylist

A quick googling gives these options for Linux

1. Unmount and mount the partition holding the files
2. sync && echo 1 > /proc/sys/vm/drop_caches

Use SysInternal's RAMMap app.

The Empty / Empty Standby List menu option will clear the Windows file cache.

For Windows XP, you should be able to clear the cache for a specific file by opening the file using CreateFile with the FILE_FLAG_NO_BUFFERING options and then closing the handle. This isn't documented, and I don't know if it works on later versions of Windows, but I used this long ago when writing test code to compare file compression libraries. I don't recall if read or write access affected this trick.