topic Re: VTune fails: ProcessSectionHeaders: 927: unknown section type 0x6fff4c04 in Analyzers

VTune fails: ProcessSectionHeaders: 927: unknown section type 0x6fff4c04

wenzeljakob — Mon, 23 Nov 2020 21:36:18 GMT

Hi,

I am unable to profile applications using VTune, which fails using the following error message

$ /opt/intel/vtune_profiler_2020/bin64/vtune --collect threading my_application

tune: Collection started. To stop the collection, either press CTRL-C or enter from another console window: vtune -r /home/wjakob/enoki-jit/r003tr -command stop.
vtune: Error: [Instrumentation Engine]: Source/pin/elfio/img_elf.cpp: ProcessSectionHeaders: 927: unknown section type 0x6fff4c04 for sec[150,.deplibs] in /lib/x86_64-linux-gnu/libc++.so.1
vtune: Collection failed.
vtune: Internal Error

The issue seems highly reminiscent to the following forum message, where the workaround was to use hardware-based sampling. I was interested in "--collect threading" mode, where that variant is not available, however.

In case it is relevant, this program was built using Clang 10 with libc++. I am using the latest version of VTune (2020_update3) on Ubuntu 20.04.
Any suggestions would be greatly appreciated,
Wenzel Jakob

Re: VTune fails: ProcessSectionHeaders: 927: unknown section type 0x6fff4c04

wenzeljakob — Mon, 23 Nov 2020 21:45:18 GMT

A potentially useful data point regarding this issue: if the application is built using GCC (& linked against libstdc++), everything works as expected. But building a C++ application using Clang 10, and linking against libstdc++ appears to cause the issue.

Re: VTune fails: ProcessSectionHeaders: 927: unknown section type 0x6fff4c04

Kirill_U_Intel — Tue, 24 Nov 2020 08:46:48 GMT

There is hardware version of threading analysis. We could not catch sync objects in such case but probably you find what you need.

vtune -collect threading -knob sampling-and-waits=hw

It will be great if you share small source reproducer with compiler/linker flags to try that on our side.

Thanks, Kirill

Re: VTune fails: ProcessSectionHeaders: 927: unknown section type 0x6fff4c04

wenzeljakob — Tue, 24 Nov 2020 08:52:15 GMT

Doesn't take much to reproduce

#include <iostream> int main(int, char **) { std::cout << "Hello world" << std::endl; }

To compile:

$ clang++ test.cpp -o test -stdlib=libc++

$ /opt/intel/vtune_profiler_2020/bin64/vtune --collect threading test

This involves the following packages (on Ubuntu 20.04):

ii clang 1:10.0-50~exp1 amd64 C, C++ and Objective-C compiler (LLVM based)
ii libllvm10:amd64 1:10.0.0-4ubuntu1 amd64 Modular compiler and toolchain technologies, runtime library
ii llvm-10 1:10.0.0-4ubuntu1 amd64 Modular compiler and toolchain technologies
ii libc++-10-dev:amd64 1:10.0.0-4ubuntu1 amd64 LLVM C++ Standard library (development files)
ii libc++-dev:amd64 1:10.0-50~exp1 amd64 LLVM C++ Standard library (development files)
ii libc++1-10:amd64 1:10.0.0-4ubuntu1 amd64 LLVM C++ Standard library
ii libc++abi-10-dev:amd64 1:10.0.0-4ubuntu1 amd64 LLVM low level support for a standard C++ library (development files)
ii libc++abi-dev:amd64 1:10.0-50~exp1 amd64 LLVM low level support for a standard C++ library (development files)
ii libc++abi1-10:amd64 1:10.0.0-4ubuntu1 amd64 LLVM low level support for a standard C++ library

Re: VTune fails: ProcessSectionHeaders: 927: unknown section type 0x6fff4c04

Vladimir_T_Intel — Tue, 24 Nov 2020 11:28:06 GMT

Hi wenzeljakob,

Thanks for the reproducer! The bug has been fixed and the fix will show-up in the next public release. But if you need to have it quickly with an intermediate build, you'd need to create a ticket in the http://supporttickets.intel.com/ (just mention a link to this forum thread in ticket).

-Vladimir

Re: VTune fails: ProcessSectionHeaders: 927: unknown section type 0x6fff4c04

wenzeljakob — Tue, 24 Nov 2020 12:57:39 GMT

Great, thank you! I can compile with GCC/libstdc++ for now, but it's nice to hear that libc++ will be supported.

Re: VTune fails: ProcessSectionHeaders: 927: unknown section type 0x6fff4c04

wenzeljakob — Tue, 24 Nov 2020 12:58:20 GMT

Oops, I mis-clicked and selected my own post as "solution" -- sorry about that!

Re:VTune fails: ProcessSectionHeaders: 927: unknown section type 0x6fff4c04

AthiraM_Intel — Thu, 26 Nov 2020 11:47:59 GMT

Hi,

Glad to know that your issue is resolved. We won't be monitoring this thread anymore. Kindly raise a new thread if you need further assistance.

Thanks.