Blocked state from nsight system report

Can someone explain to me what might be the causes of blocked states reported by nsight system?


I am sorry that there was no response to this earlier, your forum post was dropped in an orphaned category that the Nsys team was unaware of until this afternoon.

The blocked state corresponds to a place in the timeline where the OS was keeping the CPU from being active. This could be something like waiting for a barrier/mutex. If you zoom in/hover over the blocked state, you will see a tooltip that will indicate what the OS call was and the stack trace that got you there.


Thanks for the message. This issue is still remaining to be resolved for my program. By hovering over the blocked state, I do get more information. But I don’t see OS call or stack trace of the state. Is there a flag that I need for the compiler in order to see the stack trace from profiler? Thanks,

I can’t see the OSRT trace line in the picture you attached.

I am going to guess that you collected OSRT information, but that you didn’t have stack trace information. can you run

nsys status -e

and tell me the output?

You can find the nsys (CLI executable) in your target directory in the installation location.

Thanks for the fast reply,

I forgot to mention that I am running this on a windows workstation.

I can’t find nsys. So I run the following commands

  1. C:\Program Files\NVIDIA Corporation\Nsight Systems 2021.2.1> .\host-windows-x64\nsys-ui.exe status -e
    this will just start nsight systems
  2. PS C:\Program Files\NVIDIA Corporation\Nsight Systems 2021.2.1> .\target-windows-x64\nsys.exe status
    I got the following message
    “There are no active sessions.”


Sorry, I didn’t realize.

OSRT (Operating System Run Time) trace is not currently supported on windows.

nsys.exe is the command line, “status -e” checks the environment to determine permission limitations. “status” looks to get the session ID of any active sessions.

Since we aren’t going to be able to get more information from the OSRT trace, I would look to the areas highlighted in teal. Those are the sections of the execution that are related to what you have clicked on. That might give you the best clues.

(Also you are running 2021.2 and we released 2021.5 in November. I can’t say that I think upgrading would help, but it wouldn’t hurt).