AM6442: AM64x Linux RT SDK 9.2 -> 10.x : did the Linux scheduling change given the Linux baseline changed from 6.1 to 6.6?

Jim Mrowca

Part Number: AM6442
Other Parts Discussed in Thread: AM6411

Tool/software:

Basic scheduling questions given Bin's response to an AM6411 query - now I am inquiring for AM64x SDK 9.2 -> 10.0

1) Didn't the Linux RT scheduler change when going from the Linux 6.1 baseline to Linux 6.6?

2) If so, how significant was the impact to IPC implementation and performance between the A53 and the R5 cores? (Nick?)

thanks

Jim

0 Nick Saulnier 2 months ago

Did the Linux scheduler change?

I am not aware of a difference in Linux scheduler, but I'll let another team member comment for sure.

IPC RPMsg performance?

IPC RPMsg performance between A53 Linux and R5F cores is much more controlled in Linux 6.6 because of changes to the underlying mailbox driver. Starting in kernel 6.6, we allow the mailbox driver to be prioritized above other tasks, leading to more deterministic behavior. You can see my latest test results here:
https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1410313/am6442-communication-latency-issues-between-a53-and-r5-in-a-linux-rt-system/5434861#5434861

Please note that RT Linux is still NOT a true real-time system. By looking at those histogram plots you can see that the behavior is much better contained than in kernel 6.1 (see this older response: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1388960/sk-am64b-rpmsg-between-a53-and-r5-performance-update/5328241#5328241 ). However, there is still the chance that longer latencies will rarely be seen over long runtimes.

Regards,

Nick

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