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:

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

col a

col b

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’