Sysinternals Freeware - Mark Russinovich & Bryce Cogswell


Copyright 1997-2000 Mark Russinovich
Last Updated: February 17, 2000 v1.6a


One of the most annoying characteristics of NT is its lack of support for tuning various system performance settings such as the foreground and background process quanta (a quantum is the time-slice, or length of time a thread will run without being pulled off the CPU for another thread to run). On NT Server, the quanta are fixed for both foreground and background processes at 120ms, and on NT Workstation a background process has a quantum of 20ms, and a foreground process has a quantum of either 20, 40, or 60ms (the foreground boost slider in the Performance tab of the System applet in the Control Panel determines which).

Well, here's a little applet that will let you "frob" the quanta to your liking. The new quanta will immediately be applied to every process in the system and will also affect new processes that are created.

See my Windows 2000 Quantums for information on quantum configurability hidden in Windows 2000.

Installation and Use

Frob only works on NT 4.0 Final Release, SP1, SP2, SP3, SP4, SP5 and SP6a (note: it does not run on SP6). When you start Frob, it will display the system's current foreground and background quanta. Simply enter different values and press Apply. Press Reset to restore the quanta to those that existed at the startup of Frob. Note that values 0 and greater than 420ms are effectively equal to a quantum of 10ms, and that Frob does not check against these ranges.

Another way to use Frob is to specify the foreground and background quantums on the command line:

Usage: ntfrob [foreground quantum] [background quantum]

How it Works

Frob consists of a GUI that communicates with a device driver to directly lookup and frob NT's internal (and otherwise inaccessible) quantum matrix. In addition, it travels the undocumented list of processes and adjusts the quanta they are assigned. When a thread starts a new quantum, it inherits the quantum value from its process. Similarly, when a new process is created, it adopts the quantum setting of its parent.

Download Frob (16KB)

Back to Top