Linux uses free RAM to store pages of disk files to speed up overall disk access.
However for the purposes of benchmarking, I want to test the disk read speed and I don't want that speed measurement to be thrown off by disk file data already cached in RAM. Is there a way to either
A) ensure that a new file that I create will not be stored in RAM, or
B) purge RAM of any particular disk file?
I should also say I want to avoid the use of sudo.