Topology

The topology of a datacenter is defined using a JSON file. A topology consist of one or more clusters. Each cluster consist of at least one host on which jobs can be executed. Each host consist of one or more CPUs, a memory unit and a power model.

Code

The code related to reading and processing topology files can be found here

Schema

The schema for the topology file is provided in schema. In the following section, we describe the different components of the schema.

Cluster

variable	type	required?	default	description
name	string	no	Cluster	The name of the cluster. This is only important for debugging and post-processing
count	integer	no	1	The amount of clusters of this type are in the data center
hosts	List[Host]	yes	N/A	A list of the hosts in a cluster.

Host

variable	type	required?	default	description
name	string	no	Host	The name of the host. This is only important for debugging and post-processing
count	integer	no	1	The amount of hosts of this type are in the cluster
cpuModel	CPU	yes	N/A	The CPUs in the host
memory	Memory	yes	N/A	The memory used by the host
power model	Power Model	yes	N/A	The power model used to determine the power draw of the host

CPU

variable	type	Unit	required?	default	description
name	string	N/A	no	unknown	The name of the CPU.
vendor	string	N/A	no	unknown	The vendor of the CPU
arch	string	N/A	no	unknown	the micro-architecture of the CPU
count	integer	N/A	no	1	The amount of cpus of this type used by the host
coreCount	integer	count	yes	N/A	The number of cores in the CPU
coreSpeed	Double	Mhz	yes	N/A	The speed of each core in Mhz

Memory

variable	type	Unit	required?	default	description
name	string	N/A	no	unknown	The name of the CPU.
vendor	string	N/A	no	unknown	The vendor of the CPU
arch	string	N/A	no	unknown	the micro-architecture of the CPU
count	integer	N/A	no	1	The amount of cpus of this type used by the host
memorySize	integer	Byte	yes	N/A	The number of cores in the CPU
memorySpeed	Double	?	no	-1	The speed of each core in Mhz. PLACEHOLDER: this currently does nothing.

Power Model

variable	type	Unit	required?	default	description
vendor	string	N/A	yes	N/A	The type of model used to determine power draw
modelName	string	N/A	yes	N/A	The type of model used to determine power draw
arch	string	N/A	yes	N/A	The type of model used to determine power draw
totalPower	Int64	Watt	no	max long	The power draw of a host when using max capacity in Watt
carbonTracePath	string	N/A	no	null	Path to a carbon intensity trace. If not given, carbon intensity is always 0.

Examples

In the following section, we discuss several examples of topology files. Any topology file can be verified using the JSON schema defined in schema.

Simple

The simplest data center that can be provided to OpenDC is shown below:

{
    "clusters": [
        {
            "hosts": [
                {
                    "cpu":
                    {
                        "coreCount": 16,
                        "coreSpeed": 1000
                    },
                    "memory": {
                        "memorySize": 100000
                    }
                }
            ]
        }
    ]
}

This creates a data center with a single cluster containing a single host. This host consist of a single 16 core CPU with a speed of 1 Ghz, and 100 MiB RAM memory.

Count

Duplicating clusters, hosts, or CPUs is easy using the "count" keyword:

{
    "clusters": [
        {
            "count": 2,
            "hosts": [
                {
                    "count": 5,
                    "cpu":
                    {
                        "coreCount": 16,
                        "coreSpeed": 1000,
                        "count": 10
                    },
                    "memory": 
                    {
                        "memorySize": 100000
                    }
                }
            ]
        }
    ]
}

This topology creates a datacenter consisting of 2 clusters, both containing 5 hosts. Each host contains 10 16 core CPUs. Using "count" saves a lot of copying.

Complex

Following is an example of a more complex topology:

{
    "clusters": [
        {
            "name": "C01",
            "count": 2,
            "hosts": [
                {
                    "name": "H01",
                    "count": 2,
                    "cpus": [
                        {
                            "coreCount": 16,
                            "coreSpeed": 1000
                        }
                    ],
                    "memory": {
                        "memorySize": 1000000
                    },
                    "powerModel": {
                        "modelType": "linear",
                        "idlePower": 200.0,
                        "maxPower": 400.0
                    }
                },
                {
                    "name": "H02",
                    "count": 2,
                    "cpus": [
                        {
                            "coreCount": 8,
                            "coreSpeed": 3000
                        }
                    ],
                    "memory": {
                        "memorySize": 100000
                    },
                    "powerModel": {
                        "modelType": "square",
                        "idlePower": 300.0,
                        "maxPower": 500.0
                    }
                }
            ]
        }
    ]
}

This topology defines two types of hosts with different coreCount, and coreSpeed. Both types of hosts are created twice.

With Units of Measure

Aside from using number to indicate values it is also possible to define values using strings. This allows the user to define the unit of the input parameter.

{
    "clusters": [
        {
            "count": 2,
            "hosts" :
            [
                {
                    "name": "H01",
                    "cpuModel":
                    {
                        "coreCount": 8,
                        "coreSpeed": "3.2 Ghz"
                    },
                    "memory": {
                        "memorySize": "128e3 MiB",
                        "memorySpeed": "1 Mhz"
                    },
                    "powerModel": {
                        "modelType": "linear",
                        "power": "400 Watts",
                        "maxPower": "1 KW",
                        "idlePower": "0.4 W"
                    }
                }
            ]
        }
    ]
}