Speakers
Description
This talk covers ARM SMMU contiguous-hint support in Linux stage-1 page tables and the ARM-SMMU PMU support used to measure its impact. The work enables larger effective mappings, including 64K regions built from 16 adjacent 4K entries, and extends IOMMU map/unmap support for mixed and larger mapping sizes. In parallel, ARM-SMMU PMU integration exposes TBU and TCU counters through perf, including access, TLB allocate/read/write, cache-hit, and page-table-walk events, with StreamID-based filtering for workload attribution.
We present page-table behavior observed in tracing alongside translation-side measurements from PMU counters. Early measurements show measurable gains from mixed 4K/64K mappings with contiguous hint enabled: lower TLB allocation pressure and lower elapsed time versus a 4K-only baseline.
The talk also highlights different pmu counters used, invalidation effects, and how we can evaluate real SMMU translation performance.