EMULATOR (SOLVER)

NAME

SYNOPSIS

DESCRIPTION

The solver is the part of the suite that actually computes temperatures using finite-element analysis. It receives component utilizations from a trace file or from monitoring daemons. If the utilizations come from a file, i.e. the system is run offline, the end result is another file containing all the usage and temperature information for each component in the system over time. If the utilizations come from the monitoring daemons (each of which running on a different machine than the solver), the applications or system software can query the solver for temperatures. Regardless of where the utilizations come from, the solver computes temperatures at regular intervals; one iteration per second by default. All objects and air regions start the emulation at a user-defined initial air temperature.

This server is the key part of the infrastructure for the temperature emulator suite. It reads a heat and an airflow graph, and then listens to machine usage messages to create a representation of the state in question.

-m file.dot

The machine configuration file to use is a required parameter. It should contain the heat and the airflow graphs of the machine.

-c file.dot

The cluster configuration file to use (optional argument). If it is not present, machine inlet temperatures will remain fixed.

-p port

The port to connect to on the server. Defaults to 8367.

-d

Debug mode. No daemon created on background.

-v

Verbose mode, do not daemonize, and prints messages on screen (silent mode is default).

-b

Prints the emulated temperatures before the air movement. It is a special verbose mode. Do not daemonize.

-l file.log

Log all monitor messages to this file.

-f file.log

Reads utilization and temperature values from a trace file, printing out emulated temperatures.

-w

Number of warm-up iterations.

-h

A brief summary of usage.

RULES FOR BUILDING HEATFLOW GRAPHS

A heatflow graph is a data structure in the following basic format:

graph mX {
    graph [quantity=Y,fanspeed=FLOAT,Tinlet=FLOAT]
    componentA1 [T0=FLOAT,label="NAME",mass=FLOAT,kconstant=FLOAT, Q="NAME:(x1,y1)(x2,y2)"];
    componentB1 [T0=FLOAT,label="NAME",mass=FLOAT,kconstant=FLOAT];
    (...)
    /* You should define the air close to the previously defined components  */
    A1_air [T0=FLOAT, kconstant=1004]
    B1_air [T0=FLOAT, kconstant=1004]
    (...)
    /* You can define the downstream air of each component  */
    A1_downstreamair [T0=FLOAT, kconstant=1004]
    B1_downstreamair [T0=FLOAT, kconstant=1004]
    (...)
    /* Example of relationships between components */
    cpu -- cpuair [weight=0.75]
    motherboard -- cpu [weight=0.1]
}


X and Y 
The numbers X and Y matter when monitord is being used. In trace-based emulations,
both of them should be set to 1. 

However when using the monitor (online experiments),
X and Y together define a range of valid IP addresses, as well as the maximum number
of machines that can be monitored, and have their temperatures emulated. That is, 
assuming one monitor per machine, X is the rightmost byte of the smallest IP address
allowed. Y is the absolute difference between X and the rightmost byte of the largest
IP address allowed plus one. As a consequence, Y ends up being the maximum number of 
machines that can be monitored with that configuration. The machines can either have 
consecutive or sparse addresses, as long as their rightmost bytes fall into that range. 
For example, our network has 5 hosts:



hostA 192.168.7.5


hostB 192.168.7.6


hostC 192.168.7.7


hostD 192.168.7.8


hostE 192.168.7.9



Suppose that we want to allow the monitoring of any 2 machines in the range hist to hostage.
Our configuration should be something like this:

graph m6 {
  graph [quantity=4,fenced=FLOAT,Taint=FLOAT]

digraph aX {
    graph [quantity=Y,fanspeed=FLOAT,Tinlet=FLOAT]
    inlet [T0=FLOAT, kconstant=1004]
    exhaust [T0=FLOAT, kconstant=1004]

    inlet -> macair [weight=0.9]
    inlet -> cpuair [weight=0.1]

    macair -> exhaust [weight=1]
    cpuair -> exhaust [weight=1]
}