hyperactive dhclient?

[Lowell Gilbert]

Robert Huff <roberthuff at rcn.com> writes:

> 	Normally, I expect dhclient to run at startup and then
> disappear into the background.
> 	Today - in the process of diagnosing other troubles - I ran
> into this from top:
> 
> last pid: 48344;  load averages:  3.30,  2.85,  2.46    up 0+19:50:53  14:17:04
> 127 processes: 3 running, 122 sleeping, 1 zombie, 1 lock
> CPU states: 42.4% user, 12.5% nice, 42.4% system,  2.7% interrupt,  0.0% idle
> Mem: 146M Active, 22M Inact, 100M Wired, 2560K Cache, 60M Buf, 222M Free
> Swap: 2048M Total, 310M Used, 1738M Free, 15% Inuse, 156K In
> 
>   PID USERNAME    THR PRI NICE   SIZE    RES STATE    TIME   WCPU COMMAND
>   226 _dhcp         1 111    0  1528K   268K *Giant  31:04 12.74% dhclient
> 
> 
> 	Now I assume "*Giant" means the Giant Lock ... which is another
> thing I've never seen before.  Not for dhclient, and not for
> anything else.

I don't think that tells you much other than that dhclient is waiting
to acquire the giant lock.  Which is probably for access to the
network card -- my guess would be that you are using a NIC that hasn't
been rewritten for fine-grained locking.

> 	Gut reaction says this is not a good thing.  On the other hand
> my gut reaction has often been wrong.  Is there a legitimate reason
> for this much activity?  If not, how do I figure out what's broken?
> 	(I'm running
> 
> FreeBSD 7.0-CURRENT #0: Wed Jan  4 13:41:21 EST 20
> 
> 	but this is as much a question about dhcp as it is about
> any particular version.)

Hard to say.  I'd start by looking at the traffic it's sending and
receiving.  A clue is likely to turn up there...

-- 
Lowell Gilbert, embedded/networking software engineer, Boston area
		http://be-well.ilk.org/~lowell/