[CentOS] Load Average ~0.40 when idle

[Nataraj]

On Sat, 2008-07-19 at 16:54 -0700, listmail wrote:
> On Sat, 19 Jul 2008 19:28:55 -0400, Dan Halbert wrote
> > listmail wrote:
> >  >it has the same problem: load average 0.4 when idle.
> > 
> > If you disconnect or shut down the NIC(s), does that make any difference?
> >
> Good suggestion. Disconnecting the Ethernet cables from the NICs did not
> make a difference. However, shutting down the interfaces (e.g ifdown eth0,
> ifdown eth1) did cut the load average down to nothing (0.00).
> 
> So it wasn't actual traffic, but something that the interfaces were doing,
> or something that was trying to talk to one or both of them.
> 
> Does this result suggest anything else?

You could try running powertop to see if it tells you anything more
about interrupts being generated.  If you're not using IPV6, you could
disable it.  If you didn't want to keep installing things, you could try
the live CDs from various distributions that have some of the newer
kernel features enabled, such as fedora.

I am running vmware server and found that when I compile a recent custom
kernel (in the VM) with the tickless kernel  and several other options
enabled, it substantially reduces wasted CPU cycles.  This is somewhat
different from running on real hardware though.  Even so, on the various
laptop lists, people talk about how the machines run hotter when their
constantly processing unnecessary interupts.

Here are just some of the things I've turned on, though I can't remember
all of them:

CONFIG_TICK_ONESHOT=y CONFIG_NO_HZ=y CONFIG_HIGH_RES_TIMERS=y
CONFIG_PARAVIRT_GUEST=y (paravirtuailized Guest/VMU Guest support)
CONFIG_PARAVIRT=y CONFIG_VMI=y CONFIG_HIBERNATION=y

Nataraj