Random access talk

1. Is RISC-V ready for HPC workloads?
Patrick Diehl
Joint work with: Gregor Daiß, Steven R. Brandt, Alireza Kheirkhahan,
Hartmut Kaiser, Christopher Taylor, and John Leidel
Louisiana State University
patrickdiehl@lsu.edu
April 24, 2024
P. Diehl (CCT/Physics/LSU) Is RISC-V ready for HPC workloads? April 24, 2024 1 / 9

2. First RISC-V hardware for HPC workloads is available!
Two VisionFive Open Source RISC-V
single board computers with
Quad-core StarFive JH7110 64-bit
CPU and 8GB LPDDR4 System
Memory.
Two MILK-V with desktop
computers with 64-core SOPHON
SG2042 64-bit CPU and 128 GB
DDR System Memory.
P. Diehl (CCT/Physics/LSU) Is RISC-V ready for HPC workloads? April 24, 2024 2 / 9

3. How tricky was it to get the HPC stack working?
Common tools
Linux operation system ✓
GNU compiler collection ✓
MPI ✓
SLURM ✓
Specific tools
The C++ standard library for parallelism and concurrency (HPX) ✓
Single source code modification for timers to use the RISC-V
RDTIME instruction.
Kokkos ✓
Kokkos built out of the box, however, adaption to CMake was needed
to pass the correct compiler flags for RISC-V architecture.
P. Diehl and et. al, Evaluating HPX and Kokkos on RISC-V using an astrophysics application Octo-Tiger,
10.1145/3624062.3624230
P. Diehl (CCT/Physics/LSU) Is RISC-V ready for HPC workloads? April 24, 2024 3 / 9

4. Real production runs: DWD merger
ρ = 0.1
ρ = 1
ρ = 5
ρ = 20
ρ = 100
ρ = 500
in g/cm3
S. Shiber, and et. al, Hydrodynamic simulations of wd-wd mergers and the origin of RCB stars, 2024.
P. Diehl (CCT/Physics/LSU) Is RISC-V ready for HPC workloads? April 24, 2024 4 / 9

5. Single board computers: Performance
0 200 400 600 800 1,000
1-RISC
1-Fugaku
2-RISC-TCP
2-RISC-MPI
2-Fugaku-MPI
91
168
140
778
1,091
Cells processed per second
Figure: Distributed scaling for a single node and two nodes using TCP or MPI for
communication on RISC-V. We only used 4 Fugaku cores on a node.
P. Diehl (CCT/Physics/LSU) Is RISC-V ready for HPC workloads? April 24, 2024 5 / 9

6. Single board computers: Performance: Energy
consumption
0 0.5 1 1.5 2
1-RISC
1-Fugaku
2-RISC-TCP
2-RISC-MPI
2-Fugaku-MPI
1.19
1.28
1.53
0.92
1.46
Wh
P. Diehl (CCT/Physics/LSU) Is RISC-V ready for HPC workloads? April 24, 2024 6 / 9

7. Desktop machines: Performance
0 200 400 600 800
1
1
2
2
105.92
176.11
163.64
225.14
Processed sub-grids per time step
#
nodes
Level 11 (initial mesh)
RISC-V
A64FX
Note that we used all cores of the nodes. Recall that an A64FX node has 48 cores and a RISC-V node has 64 cores.
P. Diehl (CCT/Physics/LSU) Is RISC-V ready for HPC workloads? April 24, 2024 7 / 9

8. Desktop machines: Energy consumption
0 1,000 2,000 3,000
1
1
2
2
1,854.7
2,230.8
2,000.7
2,908.3
Wh
#
nodes
Level 11 (initial mesh)
RISC-V
A64FX
P. Diehl (CCT/Physics/LSU) Is RISC-V ready for HPC workloads? April 24, 2024 8 / 9

9. P. Diehl (CCT/Physics/LSU) Is RISC-V ready for HPC workloads? April 24, 2024 9 / 9