ThreadX SMP only running one thread at a time

Collin 0

As the title states, I am running the SMP version of ThreadX and despite having 4 cores to work with, I am only seeing one thread running at a given time. I am a little uncertain if this is the expected behavior or not. I found this line in the documentation:

At any given moment, only one thread is in an executing state. This is because a thread in the executing state has control of the underlying processor.

which would indicate that it is expected behavior, but that line is copy-paste from the documentation for the non-SMP version so I'm not sure if it is accurate or not. In my mind, only having a single thread running at a time would defeat the purpose of SMP so I'm wondering if this is intended and there is some technical reason why only one thread can run, or if there is perhaps something wrong with my ThreadX setup.

1 answer

Cindy Deng 6 Reputation points

2023-02-09T16:57:13.6+00:00

Hi @Collin,

ThreadX SMP should enable multiple threads running across multiple cores at the same time. With your 4 core system, you can expect 4 threads to be in the executing state simultaneously, one thread on each core. I would recommend you double check any configuration files such as tx_user.h and tx_port.h in your project, specifically any options related to cores with SMP enabled. Do you mind sharing which SMP port are you using?

Thanks,

Cindy
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Collin 0 Reputation points

2023-02-09T19:13:30.13+00:00

I am based of of the Cortex A53 SMP port. I had to modify some of the startup code to get it running on the hardware I'm using, but the ThreadX settings are all unchanged.

Cindy Deng 6 Reputation points

2023-02-14T22:06:39.6033333+00:00

Hi Collin,

We tested the A53 SMP GNU and AC6 ports on our end and we're seeing multicore threading. If you don't mind sharing, what modifications did you make to the startup file? Also what hardware are you using?

There are some other tickets opened in the past about building the A53 SMP port, here is a few links in case you find anything useful

https://video2.skills-academy.com/en-us/answers/questions/750915/threadx-rtos-for-cortex-a53-in-smp-mode

https://video2.skills-academy.com/en-us/answers/questions/514180/thread-smp-cortex-a53-4-core

Thanks,
Cindy

Collin 0 Reputation points

2023-02-15T15:11:07.9+00:00

I am working on a Xilinx Zynq UltraScale+ MPSoC. The modifications I had to make were mainly with the GIC as the US+ has a GIC400 which uses v2 rather than the v3 that the port was designed for. I also had to modify the memory setup slightly to reflect the memory layout on the US+.

To clarify, when you say you see multicore threading, do you mean that multiple threads are running concurrently on the available cores? I have seen multicore threading to the extent that each of the cores on the board get used, but they do not appear to be getting used concurrently (seen both in TraceX and by the fact that 1 high priority thread blocks other threads from running).

Scott Azure RTOS 4,051 Reputation points

2023-02-15T17:07:19.9366667+00:00

Hi Collin, can you please send an email to rtos_support@microsoft.com and we'll get you a working example for the ZCU102.

AshokPeddakotla-MSFT 33,026 Reputation points

2023-02-16T16:33:56.9433333+00:00

Collin Did you get a chance to see previous response? Please send an email as Scott suggested for further assistance.
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ThreadX SMP only running one thread at a time

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