[Beowulf] Definition of HPC

[Max R. Dechantsreiter]

> "sudo sysctl -w vm.drop_caches=3" is the smarter way to do it,
> or a fixed executable with sudo.  or a fixed executable with suid.
> or better yet: have the system do it when appropriate,
> since inappropriate drop_caches could cause problems.

What problems?

 	http://linux-mm.org/Drop_Caches

 	"This is a non-destructive operation and will only free things that are completely unused. Dirty objects will continue to be in use until written out to disk and are not freeable. If you run "sync" first to flush them out to disk, these drop operations will tend to free more memory."