Linux 6.18 on Raspberry Pi 500+ Lifts SVT-AV1 Encoding, Regresses JSON Parsing
Phoronix benchmarks show updated Raspberry Pi OS with Linux 6.18 LTS delivers small but consistent SVT-AV1 encoding improvements on Raspberry Pi 500+ hardware, while some JSON parsing workloads regressed. The results are relevant for teams evaluating low-cost ARM-based encoding solutions.
Key Takeaways
- SVT-AV1 encoding improved on Linux 6.18 across presets 5, 8, and 13 at both 1080p and 4K Bosphorus test inputs, with Linux 6.18 winning every benchmark configuration
- Sonic JSON parsing regressed on Linux 6.18 — Linux 6.12 was fastest across decode, encode, get, and set tests, despite both using the same GCC 14.2 compiler
- simdjson throughput was essentially unchanged between kernel versions, with Linux 6.18 winning only the json2msgpack test
- OCUDU software-defined radio benchmarks showed measurable gains on Linux 6.18 for both PDSCH and PUSCH processor throughput tests
Why It Matters
The results confirm that kernel-level changes in Linux 6.18 can positively impact CPU-based AV1 encoding workloads on low-cost ARM hardware, even if the gains are modest. For teams evaluating Raspberry Pi 500+ as a lightweight encoding node, the kernel upgrade is a net positive for video pipelines — but the JSON parsing regression is a reminder that kernel switches carry workload-specific tradeoffs. Watch whether the JSON regression persists through the 6.18.y stable patch series or gets isolated to a specific subsystem change.
Additional Context
The Raspberry Pi 500+ launched in September 2025 at $200, built on the Raspberry Pi 5 platform with a 2.4GHz quad-core Arm Cortex-A76 CPU, 16GB of LPDDR4X-4267 RAM, and a pre-installed 256GB NVMe SSD (per Raspberry Pi Foundation, September 2025). The device is positioned for coding, browsing, thin-client use cases, and retro computing — not explicitly for video encoding, but its 16GB memory and NVMe storage make it a plausible low-cost encoding test bed.
Linux 6.18 was released by Linus Torvalds on November 30, 2025, and was officially designated an LTS kernel in December 2025, with support projected through December 2027 (per 9to5Linux, December 2025). Key features include the new "sheaves" memory management code, AccECN congestion-control support, and the Rust binder driver. Phoronix noted at release that 6.18 showed no significant regressions in general benchmarks versus 6.17.
SVT-AV1 itself has received substantial ARM optimization investment over the past year. Version 3.0.0, released February 2025, delivered 10–25% high-bitdepth encoding improvements on ARM via Neon and SVE2 optimizations (per SVT-AV1 GitLab changelog). Version 4.0.0, released January 2026, added a further ~5% average improvement for high-bitdepth encoding on ARM. Phoronix separately benchmarked SVT-AV1 on the System76 Thelio Astra ARM desktop (Ampere Altra, 128-core) in 2025, confirming that ARM-side AV1 encoding performance has been closing the gap with x86, though it still trails Intel and AMD platforms.
Read full article at phoronix.com
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