When and how IRAM is used?

Based on the info from Tegra Linux Driver
IRAM is the Memory local to the video hardware engine.

I am use gstreamer to stream the video from an USB camera.
Below is the gstreamer code launched from OpenCV VideoCapture:
“v4l2src device=/dev/video0
! video/x-raw, format=UYVY, width=2592, height=1944, framerate=24/1
! nvvidconv ! video/x-raw(memory:NVMM), format=I420
! tee name=camNVMM ! queue ! nvv4l2h264enc maxperf-enable=true insert-vui=true insert-sps-pps=1 bitrate=10000000
! tee name=h264_stream ! queue ! h264parse ! rtph264pay ! udpsink clients=
h264_stream. ! queue ! h264parse ! matroskamux ! filesink location=test_h264.mkv
camNVMM. ! queue ! nvvidconv ! video/x-raw, format=GRAY8, width=640,height=480 ! appsink”

Below is the tegrastat output during the video streaming and OpenCV based image processing running at Jetson Nano.

RAM 2229/3956MB (lfb 1x512kB) SWAP 18/1978MB (cached 0MB) IRAM 0/252kB(lfb 252kB) CPU [80%@1479,52%@1479,53%@1479,51%@1479] EMC_FREQ 26%@1600 GR3D_FREQ 4%@153 NVENC 716 APE 25 PLL@43.5C CPU@46.5C iwlwifi@52C PMIC@100C GPU@44.5C AO@54C thermal@45.5C POM_5V_IN 5304/5541 POM_5V_GPU 156/186 POM_5V_CPU 1647/1722

The IRAM is NOT used (IRAM 0/252kB).
My questions are:

  • Why IRAM is not used?
  • How can it be used?


Please check [Figure 1: Tegra X1 Processor Block Diagram] in TRM:
Jetson Download Center | NVIDIA Developer

The IRAMs are for ARM7. The core is used in bootloader stage and after booting to kernel/user space, it is not used. So you always see it at 0.