dhclient taking all cpu
Brooks Davis
brooks at one-eyed-alien.net
Wed Jul 27 19:39:02 GMT 2005
On Wed, Jul 27, 2005 at 02:35:06PM -0500, Eric Anderson wrote:
> Brooks Davis wrote:
> >On Tue, Jul 26, 2005 at 04:39:33PM -0700, Brooks Davis wrote:
> >
> >>On Tue, Jul 26, 2005 at 06:53:17PM -0400, Jung-uk Kim wrote:
> >>
> >>>On Tuesday 26 July 2005 04:00 pm, Wilko Bulte wrote:
> >>>
> >>>>On Tue, Jul 26, 2005 at 12:33:24PM -0700, Brooks Davis wrote..
> >>>>
> >>>>
> >>>>>On Mon, Jul 25, 2005 at 10:39:09PM -0400, Mike Jakubik wrote:
> >>>>>
> >>>>>>On Mon, July 25, 2005 9:54 pm, Brooks Davis said:
> >>>>>>
> >>>>>>>>>Probably something wrong with your interface, but you
> >>>>>>>>>havent't provided any useful information so who knows. At
> >>>>>>>>>the very least, I need to know what interface you are
> >>>>>>>>>running on, something about it's status, and if both
> >>>>>>>>>dhclient processes are running.
> >>>>>>>>
> >>>>>>>>The interface is xl0 (3Com 3c905C-TX Fast Etherlink XL), and
> >>>>>>>>it worked in this machine fine for as long as i remember.
> >>>>>>>>This seems to have happened since a recent cvsup and
> >>>>>>>>buildworld from ~6-BETA to 7-CURRENT. I rebooted three
> >>>>>>>>times, and the problem occured rougly a minute after bootup.
> >>>>>>>>On the fourth time however, it seems to be ok so far.
> >>>>>>>
> >>>>>>>That sounds like a problem with the code that handles the
> >>>>>>>link state notifications in the interface driver. The
> >>>>>>>notifications are a reletivly new feature that we're only now
> >>>>>>>starting to use heavily so there are going to be bumps in the
> >>>>>>>road. It would be intresting to know if you see link state
> >>>>>>>messages promptly if you plug and unplug the network cable.
> >>>>>>
> >>>>>>It seems to be back at it again, this time it took longer to
> >>>>>>kick in. Here is a "ps auxw|grep dhclient" :
> >>>>>>
> >>>>>>_dhcp 219 93.5 0.2 1484 1136 ?? Rs 8:49PM
> >>>>>>5:06.00 dhclient: xl0 (dhclient)
> >>>>>>root 193 0.0 0.2 1484 1088 d0- S 8:49PM
> >>>>>>0:00.02 dhclient: xl0 [priv] (dhclient)
> >>>>>>
> >>>>>>top:
> >>>>>>
> >>>>>> PID USERNAME THR PRI NICE SIZE RES STATE TIME
> >>>>>>WCPU COMMAND 219 _dhcp 1 129 0 1484K 1136K RUN
> >>>>>> 9:33 94.24% dhclient
> >>>>>>
> >>>>>>Nothing in dmesg about link state changes on xl0. Unplugging
> >>>>>>and replugging the network cable results in link state
> >>>>>>notification within a couple seconds.
> >>>>>
> >>>>>Could you see what happens if you run dhclient in the foreground?
> >>>>>Just running "dhclient -d xl0" should do it. I'd like to know
> >>>>>what sort of output it's generating.
> >>>>
> >>>>In my case it is not displaying anything:
> >>>>
> >>>>
> >>>>chuck#dhclient -d ath0
> >>>>DHCPREQUEST on ath0 to 255.255.255.255 port 67
> >>>>DHCPACK from 192.168.5.254
> >>>>bound to 192.168.5.20 -- renewal in 21600 seconds.
> >>>>
> >>>><nothing>
> >>>>
> >>>>I can tell the phenomenon occurs when my laptop fan springs to
> >>>>life:
> >>>>
> >>>>CPU states: 96.5% user, 0.0% nice, 2.7% system, 0.8% interrupt,
> >>>>0.0% idle
> >>>>Mem: 48M Active, 28M Inact, 50M Wired, 680K Cache, 34M Buf, 115M
> >>>>Free Swap: 257M Total, 257M Free
> >>>>
> >>>> PID USERNAME THR PRI NICE SIZE RES STATE TIME WCPU
> >>>>COMMAND 719 _dhcp 1 129 0 1384K 1092K RUN 2:14
> >>>>93.55% dhclient 607 root 1 98 0 34584K 21212K select
> >>>>0:09 1.81% Xorg 663 wb 4 20 0 46712K 40224K kserel
> >>>>0:27 0.00% mozilla-bin 503 root 1 8 0 1184K 796K
> >>>>nanslp 0:07 0.00% powerd
> >>>>
> >>>>Took (best guess) approx 5-10 minutes for the effect to kick in.
> >>>
> >>>FYI, I have the same issues with bge(4) and ndis(4).
> >>
> >>I've seen it on ath and em interfaces now, but am not sure what's going
> >>on. and have no idea how to reproduce the problem. As also reported by
> >>Bakul Shah, we seem to be getting into a state where receive_packet() is
> >>spinning. I'm not seeing an obvious way for this to be possible.
> >
> >
> >I think I've found it. There was a really odd typo (= instead of +) in
> >the code that handles undersized captures on the bpf socket. Please try
> >the following patch and see if it solves the problem. I'm testing here,
> >but I don't have a reliable way to trigger the bug. The fix is fairly
> >obvious so I'll commit it to head shortly.
>
> It's been 20 minutes without any issues - I think that did it. Thanks!
Great! Thanks for the report.
-- Brooks
--
Any statement of the form "X is the one, true Y" is FALSE.
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