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NOTE: The interfaces of flux-sched are being actively developed and are not yet stable. The github issue tracker is the primary way to communicate with the developers.

Fluxion: An Advanced Graph-Based Scheduler for HPC

Welcome to Fluxion¹, an advanced job scheduling software tool for High Performance Computing (HPC). Fluxion combines graph-based resource modeling with efficient temporal plan management schemes to schedule a wide range of HPC resources (e.g., compute, storage, power etc) in a highly scalable, customizable and effective fashion.

Fluxion has been integrated with flux-core to provide it with both system-level batch job scheduling and nested workflow-level scheduling.

See our resource-query utility, if you want to test your advanced HPC resource modeling and selection ideas with Fluxion in a simplified, easy-to-use environment.

Fluxion Scheduler in Flux

Fluxion introduces queuing and resource matching services to extend Flux to provide advanced batch scheduling. Jobs are submitted to Flux as usual, and Fluxion makes a schedule to assign available resources to the job requests according to its configured algorithm.

Fluxion installs two modules that are loaded by the Flux broker:

• sched-fluxion-qmanager, which manages one or more prioritized job queues with configurable queuing policies (fcfs, easy, conservative, or hybrid).
• sched-fluxion-resource, which matches resource requests to available resources using Fluxion's graph-based matching algorithm.

Building Fluxion

Fluxion requires an installed flux-core package. Instructions for installing flux-core can be found in the flux-core README.

To install our other dependencies on a dnf, apk or apt-using distro you should be able to use ./scripts/install-deps.sh to install all necessary dependencies.

Fluxion also requires the following packages to build:

Installing RedHat/CentOS Packages

sudo dnf install hwloc-devel boost-devel boost-graph libedit-devel python3-pyyaml yaml-cpp-devel

Installing Ubuntu Packages

sudo apt-get update
sudo apt install libhwloc-dev libboost-dev libboost-graph-dev libedit-dev libyaml-cpp-dev python3-yaml

Clone flux-sched, the repo name for Fluxion, from an upstream repo and prepare for configure:

git clone <flux-sched repo of your choice>
cd flux-sched

Fluxion uses a CMake based build system, and can be configured and built as usual for cmake projects. If you wish you can use one of our presets, the default is a RelWithDebInfo build using ninja that's good for most purposes:

cmake -B build --preset default
cmake --build build
cmake --build build -t install
ctest --test-dir build
# OR
cmake -B build
make -C build
make -C build check
make -C build install
# OR
cmake -B build -G Ninja
ninja -C build
ninja -C build check
ninja -C build install

If you prefer autotools style, we match the rest of the flux project by offering a configure script that will provide the familiar autotools script interface but use cmake underneath.

The build system will attempt to find a flux-core in the same prefix as specified on the command line. If -DCMAKE_INSTALL_PREFIX, or for configure --prefix, is not specified, then it will default to the same prefix as was used to install the first flux executable found in PATH. Therefore, if which flux returns the version of flux-core against which Fluxion should be compiled, then the configuration may be run without any arguments. If flux-core is side-installed, then the prefix should be set to the same prefix as was used to install the target flux-core. For example, if flux-core was installed in $FLUX_CORE_PREFIX:

cmake -B build --preset default -DCMAKE_INSTALL_PREFIX="$FLUX_CORE_PREFIX"
cmake --build build
ctest --test-dir build
cmake --build build -t install
# OR
mkdir build
cd build
../configure --prefix=${FLUX_CORE_PREFIX}
make
make check
make install

To build go bindings, you will need go (tested with 1.19.10) available, and then:

export WITH_GO=yes
cmake -B build
cmake --build build
ctest --test-dir build
cmake --build build -t install

To run just one test, you can cd into t in the build directory, then run the script from the source directory or use the usual ctest options to filter by regex:

$ cd build/t
$ ../../t/t9001-golang-basic.t
ok 1 - match allocate 1 slot: 1 socket: 1 core (pol=default)
ok 2 - match allocate 2 slots: 2 sockets: 5 cores 1 gpu 6 memory
# passed all 2 test(s)
1..2
# OR
cd build
ctest -R t9001 --output-on-failure

To run full tests (more robust and mimics what happens in CI) you can do:

ctest

Flux Instance

The examples below walk through exercising functioning flux-sched modules (i.e., sched-fluxion-qmanager and sched-fluxion-resource) in a Flux instance. The following examples assume that flux-core and Fluxion were both installed into ${FLUX_CORE_PREFIX}. For greater insight into what is happening, add the -v flag to each flux command below.

Create a comms session comprised of 3 brokers:

${FLUX_CORE_PREFIX}/bin/flux start -s3

This will create a new shell in which you can issue various flux commands such as following.

Check to see whether the qmanager and resource modules are loaded:

flux module list

Submit jobs:

flux submit -N3 -n3 hostname
flux submit -N3 -n3 sleep 30

Examine the status of these jobs:

flux jobs -a

Examine the output of the first job

flux job attach <jobid printed from the first submit>

Examine the ring buffer for details on what happened.

flux dmesg

Exit the Flux instance

exit

¹ The name was inspired by Issac Newton's Method of Fluxions where fluxions and fluents are the key terms to define his calculus. As his calculus describes the motion of points in time for time-varying variables, our Fluxion scheduler uses scalable techniques to describe the motion of scheduled points in time for a diverse set of resources.

License

SPDX-License-Identifier: LGPL-3.0

LLNL-CODE-764420