Hello,

I made a profiler in a machine with ubuntu os where no program was running, I
started it, and after aome minutes I dumped the statistics. The results of the
oreport are:

root@gen1:~# opreport --exclude-dependent --demangle=smart --symbols | head
warning: /no-vmlinux could not be found.                                  
CPU: Core 2, speed 2659.99 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask of 0x00 (Unhalted core cycles) count 100000
samples  %        app name                 symbol name
29322    85.6042  no-vmlinux               (no symbols)
2993      8.7379  python2.5                (no symbols)
991       2.8932  libc-2.8.90.so           (no symbols)
330       0.9634  ld-2.8.90.so             (no symbols)
124       0.3620  oprofiled                (no symbols)
92        0.2686  libdbus-1.so.3.4.0       (no symbols)
90        0.2628  libglib-2.0.so.0.1800.2  (no symbols)
...
...

I run the profiler again:

root@gen1:~# opreport --exclude-dependent --demangle=smart --symbols | head
warning: /no-vmlinux could not be found.
CPU: Core 2, speed 2659.99 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask of 0x00 (Unhalted core cycles) count 100000
samples  %        app name                 symbol name
16227    79.4040  no-vmlinux               (no symbols)
2978     14.5723  python2.5                (no symbols)
671       3.2834  libc-2.8.90.so           (no symbols)
240       1.1744  ld-2.8.90.so             (no symbols)
60        0.2936  libdbus-1.so.3.4.0       (no symbols)
47        0.2300  libglib-2.0.so.0.1800.2  (no symbols)
39        0.1908  oprofiled                (no symbols)
...
...

My question is: Why the 80-85% of the CPU time is used from
the kernel (no-vmlinux) since no program is running in this machine?

Anyone that can help me please?

Thank you in advance,
Thanasis Petsas