[olug] System performance with oprofile

[Vincent.Raffensberger at dtn.com]

This isn't your problem, but it's related: 
I remembered seeing a comparison/ benchmark of current distros, and it 
mentioned that Gentoo did poorly in many tests because it doesn't use 
'prelink'.
A quick search yielded this howto on setting it up in Gentoo:
http://www.gentoo.org/doc/en/prelink-howto.xml




Tim Bornholtz <tim at bornholtz.com> 
Sent by: olug-bounces at olug.org
03/06/2004 10:19 PM
Please respond to
Omaha Linux User Group <olug at olug.org>


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Subject
[olug] System performance with oprofile






I have three machines, one Gentoo, one Fedora, one Debian.  The Fedora 
and Gentoo are identical Dell laptops and the Debian is a desktop with a 
slightly faster processor.

Right now my Gentoo machine is generally sluggish and the other two 
scream at whatever I throw at them.  When I run `top` on the Gentoo box 
I see that X is using anywhere from 7 to 10% of the CPU when everything 
else is idle.  On the Fedora machine X sometimes blips up to 0.1% of CPU 
but is generally idle.

So this particular problem has been kicking my butt for way too long and 
I can't seem to figure out what the heck X is doing.

I ran oprofile for about 10 seconds when everything should have been 
idle and got this output:

CPU: CPU with RTC device, speed 1695.08 MHz (estimated)
Counted RTC_INTERRUPTS events (RTC interrupts/sec (rounded up to power 
of two)) count 1024
RTC_INTERRUPTS...|
  samples|      %|
------------------
    10313 90.0699 vmlinux
      418  3.6507 libc-2.3.3.so
      104  0.9083 i8k.o
       83  0.7249 oprofiled
       71  0.6201 ld-2.3.3.so
       71  0.6201 nvidia.o
       69  0.6026 XFree86
       55  0.4803 libglib-2.0.so.0.200.3
       48  0.4192 bash
       40  0.3493 libpthread-0.10.so
       36  0.3144 libgobject-2.0.so.0.200.3
       28  0.2445 libgdk-x11-2.0.so.0.200.4
       24  0.2096 usb-uhci.o
       19  0.1659 libvte.so.4.1.1
       14  0.1223 libX11.so.6.2

<snip>

So I see that vmlinux (the kernel) is 90% of the calls but how do I 
figure out *what* it is doing?  Are there other options to use for 
oprofile?  Are there better profiling tools for linux?  I'm at a loss 
and *really* don't want to switch distros because of this. 

By the way, the system is 1.7GHz P4 with 1GB ram.  It is a Dell Inspiron 
8200.  These stats are with kernel 2.4.22 but they are very very similar 
with 2.6.3. 

Any help would be greatly appreciated.

Thanks,
Tim

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