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 <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Marek Szyprowski <[email protected]>
Cc: Robin Murphy <[email protected]>
Signed-off-by: Barry Song <[email protected]>
---
-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 testing
+ performance 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.c
diff --git a/kernel/dma/Makefile b/kernel/dma/Makefile
index dc755ab68aab..7aa6b26b1348 100644
--- a/kernel/dma/Makefile
+++ b/kernel/dma/Makefile
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