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AM62L: AM62L Real-time Performance Issue

xi he
Prodigy 10 points

Part Number: AM62L

Hi,
We are encountering real-time performance issues while using the AM62L chip. The current SDK version in use is ti-processor-sdk-linux-rt-am62lxx-evm-11.02.08.02-Linux-x86-Install.bin, with a kernel version of 6.12.57. The issue details are as follows:
  1. 1. Core isolation coconfig.gz nfiguration was applied to CPU1, and real-time optimization parameters were set in the cmdline, as shown below:
root@am62xx-evm:/# cat /proc/cmdline
console=ttyS0,115200n8 earlycon=ns16550a,mmio32,0x02800000 ubi.mtd=ospi_nand.rootfs root=ubi0:rootfs rw rootfstype=ubifs rootwait rcu_nocb_poll rcu_nohz=1 idle=poll rcu_nocbs=1 nohz=on nohz_full=1 kthread_cpus=0 irqaffinity=0 isolcpus=managed_irq,domain,1
  1. 2. A CPU load was added to Core 1, and jitter was tested using cyclictest with the following commands:
root@am62xx-evm:/# taskset -c 1 stress-ng --cpu 1 --cpu-load 70 --vm 1 --vm-bytes 80% &
root@am62xx-evm:/# cyclictest -a 0-1 -t 2 -p 99 -m -D 0 &
  1. Under this stress load, the maximum jitter exceeded 150µs within a 10-minute test, as illustrated in the figure below:

    T: 0 (  404) P:99 I:1000 C:72252 Min:      5 Act:   11 Avg:   15 Max:     203
    T: 1 (  405) P:99 I:1500 C:48159 Min:      9 Act:   33 Avg:   33 Max:     152

We are particularly concerned about the real-time performance of Core 1, as real-time tasks in actual application scenarios will also be assigned to this core. However, the current system results deviate significantly from the 60–70µs jitter self-tested in the official documentation. We would appreciate your suggestions for real-time performance optimization.
Thank you for your support!
Attachment: Our kernel .config file.
  • 0
    TI__Guru** 109180 points

    Hello Xi,

    I always like to make sure that we have the same "known good" starting point before doing any development.

    Before attempting any core isolation, did you attempt to replicate the jitter results of the official documentation by following the exact steps in the docs? Please share the results of that test with an unmodified default SDK image:
    https://software-dl.ti.com/processor-sdk-linux-rt/esd/AM62LX/11_02_08_02/exports/docs/devices/AM62LX/linux/RT_Linux_Performance_Guide.html

    Regards,

    Nick

  • 0 in reply to Nick Saulnier
    Prodigy 10 points

    Hi Nick,

    On our own product, we have performed driver adaptation based on the official SDK, incorporating considerations specific to our product design. Following the stress test commands and cyclictest parameters described in the issue, we observed the following:
    When conducting tests strictly per the official documentation, the applied stress appears relatively light, yielding real-time performance results of approximately 69μs. However, when using our customized test commands—which simulate higher workloads aligned with actual application scenarios—the real-time performance degrades significantly.
    Given this discrepancy, we would appreciate real-time performance optimization recommendations tailored to our revised test methodology and increased load conditions.
    Regards,
    Xi