[tlug] Giving a program priority briefly

["Stephen J. Turnbull" <stephen@example.com>]

Darren Cook writes:

 > Would "single user mode" give me full speed?

I hate to differ with Josh, but "single user mode" does not give you
full speed.  Single user mode simply means you have fewer daemons than
usual running, not that the current command owns the CPU.  For
example, the kernel will always be running. :-)  That is, all of the
various housekeeping threads will be running, as well as the TCP/IP
stack, etc.

 > Is there a way to move a system into that mode, run the test, then
 > move back into my gnome desktop with all applications still open,
 > with the flick of a switch?

You could look for a real-time OS which would have options to suppress
activity of threads that the RT process doesn't call itself.  There
are ways to lock a program into memory so it won't swap.  Also, on a
multi-CPU system there are ways to lock a program onto a CPU.  And
"nice -20" is a pretty good approximation to all of the above on an
unloaded system.

However, none of this is particularly meaningful yet since you've said
nothing about the environment where the program will be running.  If
it's going to be running on a more or less loaded system, then a lot
of the issues are going to have to do with paging and so on.