On 11/24/25 13:35, Anuj gupta wrote:
This series significantly reduces the IOMMU/DMA overhead for I/O,
particularly when the IOMMU is configured in STRICT or LAZY mode. I
modified t/io_uring in fio to exercise this path and tested with an
Intel Optane device. On my setup, I see the following improvement:
- STRICT: before = 570 KIOPS, after = 5.01 MIOPS
- LAZY: before = 1.93 MIOPS, after = 5.01 MIOPS
- PASSTHROUGH: before = 5.01 MIOPS, after = 5.01 MIOPS
The STRICT/LAZY numbers clearly show the benefit of avoiding per-I/O
dma_map/dma_unmap and reusing the pre-mapped DMA addresses.
Thanks for giving it a run. Looks indeed promising, and I believe
that was the main use case Keith was pursuing. I'll fix up the
build problems for v3
--
Pavel Begunkov
