Intel ACC100 LDPC offload

Mon, 01 Jan 0001 00:00:00 +0000

Scope: hardware-accelerated LDPC encoding (PDSCH) and decoding (PUSCH) on Intel ACC100 vRAN accelerator cards, with full upper-PHY metrics instrumentation so operators can directly compare CPU-software and HW-offload performance in production logs.

Introduced in commit: aa6db7d066

Highlights

LDPC offload for both PDSCH and PUSCH the most CPU-heavy channel-coding steps move off the host and onto the accelerator.
Configuration-driven enable or disable via the DU YAML; no code changes.
Multi-VF scaling allowlisting additional ACC100 VFs automatically spreads load across them.
Unified metrics the same per-block PHY metric fields populate whether LDPC runs in software (AVX-512) or on the accelerator, enabling direct side-by-side comparison from one log format.
Measured gains on real traffic significantly lower PUSCH decode latency, tighter tail latency, higher processor throughput, and reduced upper-PHY uplink CPU (see §7).

1. Prerequisites

1.1 Hardware

Intel ACC100 PCIe card, SR-IOV capable; at least one VF exposed to the host.
x86-64 CPU with AVX2 (AVX-512 recommended for the software-fallback path).
≥ 2 GB of 2 MiB hugepages.
PCIe slot on the same NUMA node as the upper-PHY worker cores.

1.2 Software

Component	Minimum version	Notes
DPDK	22.11	Tested with 25.11; ACC100 PMD (`baseband_acc`) required.
Linux kernel	5.15+	IOMMU enabled (`intel_iommu=on iommu=pt`).
`pf_bb_config`	24.03+	PF configurator daemon; must run continuously.
DU build flags	`ENABLE_DPDK=True`, `ENABLE_PDSCH_HWACC=True`, `ENABLE_PUSCH_HWACC=True`	See §5.

1.3 Kernel and VFIO setup

# Kernel boot parameters (then update-grub + reboot):
intel_iommu=on iommu=pt hugepagesz=2M hugepages=1024

# Hugepage mount if not done by distro:
echo 1024 | sudo tee /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages

# Load VFIO modules:
sudo modprobe vfio-pci
echo 1 | sudo tee /sys/module/vfio_pci/parameters/enable_sriov # if kernel-builtin

# Create one SR-IOV VF and bind it to vfio-pci:
echo 1 | sudo tee /sys/bus/pci/devices/<ACC100_PF_BDF>/sriov_numvfs
sudo dpdk-devbind.py --bind=vfio-pci <ACC100_VF_BDF>

# Start pf_bb_config holding the PF group open with a VF token.
# The token (UUID) is required in the DU's EAL args.
sudo /opt/pf-bb-config/pf_bb_config ACC100 \
 -c /opt/pf-bb-config/acc100/acc100_config_vf_5g.cfg \
 -v <UUID> &