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Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/meson.build | 1 | ||||
| -rw-r--r-- | Documentation/software-isp-benchmarking.rst | 77 |
3 files changed, 79 insertions, 0 deletions
diff --git a/Documentation/index.rst b/Documentation/index.rst index 63fac72d..5442ae75 100644 --- a/Documentation/index.rst +++ b/Documentation/index.rst @@ -24,3 +24,4 @@ Lens driver requirements <lens_driver_requirements> Python Bindings <python-bindings> Camera Sensor Model <camera-sensor-model> + SoftwareISP Benchmarking <software-isp-benchmarking> diff --git a/Documentation/meson.build b/Documentation/meson.build index 7a58fec8..3872e0a8 100644 --- a/Documentation/meson.build +++ b/Documentation/meson.build @@ -80,6 +80,7 @@ if sphinx.found() 'lens_driver_requirements.rst', 'python-bindings.rst', 'sensor_driver_requirements.rst', + 'software-isp-benchmarking.rst', '../README.rst', ] diff --git a/Documentation/software-isp-benchmarking.rst b/Documentation/software-isp-benchmarking.rst new file mode 100644 index 00000000..b3033132 --- /dev/null +++ b/Documentation/software-isp-benchmarking.rst @@ -0,0 +1,77 @@ +.. SPDX-License-Identifier: CC-BY-SA-4.0 + +.. _software-isp-benchmarking: + +Software ISP benchmarking +========================= + +The Software ISP is particularly sensitive to performance regressions therefore +it is a good idea to always benchmark the Software ISP before and after making +changes to it and ensure that there are no performance regressions. + +DebayerCpu class builtin benchmark +---------------------------------- + +The DebayerCpu class has a builtin benchmark. This benchmark measures the time +spent on processing (collecting statistics and debayering) only, it does not +measure the time spent on capturing or outputting the frames. + +The builtin benchmark always runs. So this can be used by simply running "cam" +or "qcam" with a pipeline using the Software ISP. + +When it runs it will skip measuring the first 30 frames to allow the caches and +the CPU temperature (turbo-ing) to warm-up and then it measures 30 fps and shows +the total and per frame processing time using an info level log message: + +.. code-block:: text + + INFO Debayer debayer_cpu.cpp:907 Processed 30 frames in 244317us, 8143 us/frame + +To get stable measurements it is advised to disable any other processes which +may cause significant CPU usage (e.g. disable wifi, bluetooth and browsers). +When possible it is also advisable to disable CPU turbo-ing and +frequency-scaling. + +For example when benchmarking on a Lenovo ThinkPad X1 Yoga Gen 8, with the +charger plugged in, the CPU can be fixed to run at 2 GHz using: + +.. code-block:: shell + + sudo x86_energy_perf_policy --turbo-enable 0 + sudo cpupower frequency-set -d 2GHz -u 2GHz + +with these settings the builtin bench reports a processing time of ~7.8ms/frame +on this laptop for FHD SGRBG10 (unpacked) bayer data. + +Measuring power consumption +--------------------------- + +Since the Software ISP is often used on mobile devices it is also important to +measure power consumption and ensure that that does not regress. + +For example to measure power consumption on a Lenovo ThinkPad X1 Yoga Gen 8 it +needs to be running on battery and it should be configured with its +platform-profile (/sys/firmware/acpi/platform_profile) set to balanced and with +its default turbo and frequency-scaling behavior to match real world usage. + +Then start qcam to capture a FHD picture at 30 fps and position the qcam window +so that it is fully visible. After this run the following command to monitor the +power consumption: + +.. code-block:: shell + + watch -n 10 cat /sys/class/power_supply/BAT0/power_now /sys/class/hwmon/hwmon6/fan?_input + +Note this not only measures the power consumption in µW it also monitors the +speed of this laptop's 2 fans. This is important because depending on the +ambient temperature the 2 fans may spin up while testing and this will cause an +additional power consumption of approx. 0.5 W messing up the measurement. + +After starting qcam + the watch command let the laptop sit without using it for +2 minutes for the readings to stabilize. Then check that the fans have not +turned on and manually take a couple of consecutive power readings and average +these. + +On the example Lenovo ThinkPad X1 Yoga Gen 8 laptop this results in a measured +power consumption of approx. 13 W while running qcam versus approx. 4-5 W while +setting idle with its OLED panel on. |