On 02/11/2020 08:06, Barry Song wrote:
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 patch enables the support. Users can run specified number of threads to do dma_map_page and dma_unmap_page on a specific NUMA node with the specified duration. Then dma_map_benchmark will calculate the average latency for map and unmap.
A difficulity for this benchmark is that dma_map/unmap APIs must run on a particular device. Each device might have different backend of IOMMU or non-IOMMU.
So we use the driver_override to bind dma_map_benchmark to a particual device by: For platform devices: echo dma_map_benchmark > /sys/bus/platform/devices/xxx/driver_override echo xxx > /sys/bus/platform/drivers/xxx/unbind echo xxx > /sys/bus/platform/drivers/dma_map_benchmark/bind
For PCI devices: echo dma_map_benchmark > /sys/bus/pci/devices/0000:00:01.0/driver_override echo 0000:00:01.0 > /sys/bus/pci/drivers/xxx/unbind echo 0000:00:01.0 > /sys/bus/pci/drivers/dma_map_benchmark/bind
Cc: Joerg Roedel joro@8bytes.org Cc: Will Deacon will@kernel.org Cc: Shuah Khan shuah@kernel.org Cc: Christoph Hellwig hch@lst.de Cc: Marek Szyprowski m.szyprowski@samsung.com Cc: Robin Murphy robin.murphy@arm.com Signed-off-by: Barry Song song.bao.hua@hisilicon.com
-v3:
- fix build issues reported by 0day kernel test robot
-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()
kernel/dma/Kconfig | 8 + kernel/dma/Makefile | 1 + kernel/dma/map_benchmark.c | 296 +++++++++++++++++++++++++++++++++++++ 3 files changed, 305 insertions(+) create mode 100644 kernel/dma/map_benchmark.c
diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig index c99de4a21458..949c53da5991 100644 --- a/kernel/dma/Kconfig +++ b/kernel/dma/Kconfig @@ -225,3 +225,11 @@ config DMA_API_DEBUG_SG is technically out-of-spec. If unsure, say N.
+config DMA_MAP_BENCHMARK
- bool "Enable benchmarking of streaming DMA mapping"
- help
Provides /sys/kernel/debug/dma_map_benchmark that helps with testingperformance of dma_(un)map_page.
Since this is a driver, any reason for which it cannot be loadable? If so, it seems any functionality would depend on DEBUG FS, I figure that's just how we work for debugfs.
Thanks, John
See tools/testing/selftests/dma/dma_map_benchmark.cdiff --git a/kernel/dma/Makefile b/kernel/dma/Makefile index dc755ab68aab..7aa6b26b1348 100644 --- a/kernel/dma/Makefile +++ b/kernel/dma/Makefile