Vtune Assertion

[Nitaiklu]

Hey.

I am using Vtune from my Windows computer and the target is on a Linux remote machine. 

The Vtune version is: 2024.2.1 

The OS version on the machine is: Linux 3.10.0-1160.119.1.el7.x86_64 x86_64 (I'm using Centos 7)

When trying to analyze a process with Vtune's "attach to process", the process aborts shortly after the attachment. The collection log presents the following message:

Only user space will be profiled due to credentials lack. Consider changing /proc/sys/kernel/perf_event_paranoid file for enabling kernel space profiling.
Assertion failed: object_impl:23: (((const struct tpss_object*)obj)->magic == 0xFACEECAF) : . Please contact the technical support.
Assertion failed: object_impl:23: (((const struct tpss_object*)obj)->magic == 0xFACEECAF) : . Please contact the technical support.​

As for the warning in lines 1, I changed the setting of perf_event_paranoid but that did not help. 

This error happens when using the "Hotspot" analysis type. In "Performance Snapshot" everything works well.

What am I missing?

[Jennifer_D_Intel]

What kind of workload are you attaching to? Does it work if you run the hotspots collection with hardware event-based sampling instead of user-mode sampling?

TPSS is the underlying process which does the user-mode sampling. If you use hardware event-based sampling, it will use perf instead of tpss. TPSS works with most languages, but might run into issues with managed languages like golang.

User-mode hotspots does use perf to collect some HW events when the "Show additional performance insights" box is checked, which is why you see the recommendation about perf_event_paranoid, but it doesn't seem to be causing a problem in this case.

[Nitaiklu]

Thanks for the quick response!

First of all, I noticed I did not install the drivers properly. After doing that, I tried using "hardware event-based sampling" as you said, and it worked. For some reason, "user-mode sampling" still causes the same assertion error even though my program is C++ and C only (not any managed language).
Anyways, the hw-sampling is totally enough for my use case. If you do have any idea why user-mode is not working, pls let me know.

Thanks again! 
Nitai 

[yuzhang3_intel]

Did you try to echo '0' to 'perf_event_paranoid' like below? And if your driver is ready?

# echo 0 > /proc/sys/kernel/perf_event_paranoid

From the fetal message, VTune can't profile data in kernel space. You can see a similar issue was discussed in the following post:

https://community.intel.com/t5/Analyzers/vtune-Warning-Only-user-space-will-be-profiled-due-to/m-p/1216720#M19484

[yuzhang3_intel]

Did you try to profile the data in kernel space? User mode sampling mode only profiles the data in user space.