On Sun, Sep 19, 2010 at 9:22 PM, Maucci, Cyrille <cyrille.maucci@hp.com> wrote:
Hello,
 
why do you say no programis running?
Didn't you mean that yourself had launched no program, but have you already looked at what an 'idle' system does?
 

Yes, I mean that I have not launched any program
 
From my perspective, performance troubleshooting is a drill down approach and oprofile is already a low-level thing.
Before running oprofile, have you looked your idle system at a much higher level, like what does top or sar report?
 
Yes I have done it. The top shows that all the cores of the machine are idle:



top - 14:28:30 up 87 days,  3:59,  1 user,  load average: 0.00, 0.00, 0.00
Tasks:  90 total,   1 running,  89 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.0%us,  0.0%sy,  0.0%ni,100.0%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   2052152k total,  1117572k used,   934580k free,   260452k buffers
Swap:  6008268k total,    14464k used,  5993804k free,   445756k cached
 
You would probably be surprised.
 
++Cyrille
 

From: Thanasis [mailto:skizofrenito@gmail.com]
Sent: Sunday, September 19, 2010 8:12 PM
To: oprofile-list@lists.sourceforge.net
Subject: 80-85% of CPU time is used from the kernel in a machine that no program is running. Why?

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