Policy

MOM is designed to enable dynamic tuning of a KVM host in response to statistics that are continuously collected from the host and its running guests.
This tuning policy is described using a LISP-like mini-language as described here.

Comments

Comments are expressed with the ‘#’ symbol. When ‘#’ is encountered, it and all remaining characters on the line are ignored.

Example:

Code	Result
# This is a full line comment (+ 1 1) # This is a partial-line comment	2

Strings

Strings are created by placing text between double-quotes. Variables can be assigned string values. Sting concatenation and repetition can be performed by using the ‘+’ and ‘*’ operators.

Example:

Code	Result
"foo" "bar" # Operators on strings have the same effect as for Python (+ "Hello " "World!") (+ (* 3 "Hey ") "!") # Multi-line string "multi- line"	foo bar Hello World! Hey Hey Hey ! multi- line

Numbers

Numbers can be expressed as a floating point, integer, integer in scientific notation, hexidecimal, and octal. However, numerical results are always base 10 integers or floats. The basic arithmetic operators +, -, *, /, <<. and >> are supported and have their usual meanings.

Example:

Code	Result
10 00 # Octal .3 # The leading 0 on a float is not required (* 0 1) (+ 1 2) (/ 11 2) # Integer division (/ 11 2.0) # Floating point division (* 3 6) (- 1 9) # Negative result (* (- 8 6) 9) (>> (<< 1 4) 2) (+ 0xFF 0x1) # Hex numbers (* 011 02) (+ 0xa 10) # Numeric type mixing (+ 10.0e3 100e-2) # Scientific notation for integers and floats	10 0 0.3 0 3 5 5.5 18 -8 18 4 256 18 20 10001.0

Logic and Comparison

Compound Statements

Remember to state that the result of a compound statement is the last value in the block.

Variables and Scope

Macros

The let Statement

The if Statement

Entities

The Input Entities: Host and Guests

Input Entity Methods

Prop, Stat, StatAvg, SetVar, GetVar

Controller Entities

Control()

The with Guests Construct

External Functions

• (abs x): Return the absolute value of ‘x’