Nowadays, there are increasing requirements to benchmark the performance of dma_map and dma_unmap particually while the device is attached to an IOMMU.
This patchset provides the benchmark infrastruture for streaming DMA mapping. The architecture of the code is pretty much similar with GUP benchmark: * mm/gup_benchmark.c provides kernel interface; * tools/testing/selftests/vm/gup_benchmark.c provides user program to call the interface provided by mm/gup_benchmark.c. In our case, kernel/dma/map_benchmark.c is like mm/gup_benchmark.c; tools/testing/selftests/dma/dma_map_benchmark.c is like tools/testing/ selftests/vm/gup_benchmark.c A major difference with GUP benchmark is DMA_MAP benchmark needs to run on a device. Considering one board with below devices and IOMMUs device A ------- IOMMU 1 device B ------- IOMMU 2 device C ------- non-IOMMU Different devices might attach to different IOMMU or non-IOMMU. To make benchmark run, we can either * create a virtual device and hack the kernel code to attach the virtual device to IOMMU1, IOMMU2 or non-IOMMU. * use the existing driver_override mechinism, unbind device A,B, OR c from their original driver and bind A to dma_map_benchmark platform driver or pci driver for benchmarking. In this patchset, I prefer to use the driver_override and avoid the ugly hack in kernel. We can dynamically switch device behind different IOMMUs to get the performance of IOMMU or non-IOMMU. -v2: * add PCI support; v1 supported platform devices only * replace ssleep by msleep_interruptible() to permit users to exit benchmark before it is completed * many changes according to Robin's suggestions, thanks! Robin - add standard deviation output to reflect the worst case - check users' parameters strictly like the number of threads - make cache dirty before dma_map - fix unpaired dma_map_page and dma_unmap_single; - remove redundant "long long" before ktime_to_ns(); - use devm_add_action(); - wakeup all threads together after they are ready Barry Song (2): dma-mapping: add benchmark support for streaming DMA APIs selftests/dma: add test application for DMA_MAP_BENCHMARK MAINTAINERS | 6 + kernel/dma/Kconfig | 8 + kernel/dma/Makefile | 1 + kernel/dma/map_benchmark.c | 295 ++++++++++++++++++ tools/testing/selftests/dma/Makefile | 6 + tools/testing/selftests/dma/config | 1 + .../testing/selftests/dma/dma_map_benchmark.c | 87 ++++++ 7 files changed, 404 insertions(+) create mode 100644 kernel/dma/map_benchmark.c create mode 100644 tools/testing/selftests/dma/Makefile create mode 100644 tools/testing/selftests/dma/config create mode 100644 tools/testing/selftests/dma/dma_map_benchmark.c -- 2.25.1 _______________________________________________ iommu mailing list firstname.lastname@example.org https://lists.linuxfoundation.org/mailman/listinfo/iommu