2. Resource Graph

A resource graph contains a snapshot of the state of a cluster. This normalizes machine-specific information which common across jarvis repos. Resource graphs provide query interfaces which avoid having to repeat the same paths all over the place. This section describes the contents of a resource graph and the API available to Jarvis repos.

2.1. Resource Graph Contents

The resource graph contains information about the cluster hardware:

1. Block devices
2. Device partitions
3. Filesystem mount points
4. Capacities
5. Network protocols

NOTE: The resource-graph utility command depends on:

• fi_info
• lsblk
• df

If libfabric is installed through spack, please load it before continuing.

spack load libfabric

2.2. Building a Resource Graph Automatically

Most of the information regarding resource graphs can be introspected. The main things that are not automatic:

1. Hostfile: which machines are we introspecting?
2. What is the per-user mount point of the storage devices?

If you want jarvis to execute distributed programs, provide a hostfile. This is optional for local programs.

jarvis hostfile set /path/to/hostfile

Build the resource graph

jarvis resource-graph build +walkthrough

The resource graph will be stored under ${JARVIS_ROOT}/config/resource_graph.yaml

2.3. Storage Graph

The following command lists all block devices, their type, and their mount points:

lsblk -o NAME,SIZE,MODEL,TRAN,MOUNTPOINT

The following command lists all mounted filesystems and their capacities:

df -h

The following command lists all SPDK nvmes:

spdk_nvme list -c

NOTE: SPDK is not currently implemented

The storage resource graph parses these commands automatically.

2.4. Network Graph

To build the network graph, we collect the outputs from the following command:

fi_info

This will store the network information available per host.

2.5. CPU Graph

CPU information can be helpful for determining information such as the number of threads to use for a metadata service.

TODO.

2.6. Memory Graph

Memory information can be useful for determining things like cache sizes.

TODO.

2.7. Querying the Resource Graph

The resource graph can be queried for network and storage info.

from jarvis_util import *

rg = ResourceGraph()
rg.find_storage(shared=True, condense=True)

1.7. Future Ideas

• What if we have a smart NIC?
• What if we have FPGAs and ASICs?