Question

I got a core that looks very different from the ones I usually get – most of the threads are in __kernel_vsyscall() :

  9 process 11334  0xffffe410 in __kernel_vsyscall ()   8 process 11453  0xffffe410 in __kernel_vsyscall ()   7 process 11454  0xffffe410 in __kernel_vsyscall ()   6 process 11455  0xffffe410 in __kernel_vsyscall ()   5 process 11474  0xffffe410 in __kernel_vsyscall ()   4 process 11475  0xffffe410 in __kernel_vsyscall ()   3 process 11476  0xffffe410 in __kernel_vsyscall ()   2 process 11477  0xffffe410 in __kernel_vsyscall ()   1 process 11323  0x08220782 in MyClass::myfunc () 

What does that mean?

EDIT: In particular, I usually see a lot of threads in ‘pthread_cond_wait’ and ‘___newselect_nocancel’ and now those are on the second frame in each thread – why is this core different?

Answer 1

__kernel_vsyscal is the method used by linux-gate.so (a part of the Linux kernel) to make a system call using the fastest available method, preferably the sysenter instruction. The thing is properly explained by Johan Petersson.