FreeBSD 6 vs 8.1
mats.w.lindberg at gmail.com
Fri Mar 18 08:35:24 UTC 2011
So - after a while I've made some observations.
My problem is actually connected to arp.
My config is very static so basically I want to turn off arp requests.
Somewhere in the startup scripts I did
> sysctl -w net.link.ether.inet.max_age=2147483647 (max accepted value)
Which on freebsd-6.x worked fine.
In freebsd-8.1 this makes the kernel arp functionality go bezerk - probably
an integer overflow somewhere.
arp requests were sent countinously from my freebsd-8.1 node to others,
flooding the network.
I tried to lower this value and found that 500000000s works fine 1000000000s
does not. 500000000s is OK to me so I won't try to narrow it down more.
The reason I was suspecting swapping problems was that after a while with
the flooding going on I got a kernel panic saying 'page fault', which I
would guess is a another bug, but, with a sensible setting on the arp
timeout the kernel panic does not show itself any longer.
I've googled for my arp-setting problem but not found anything on it. So -
maybe I'm the first to see this.
Should I enter a bug report somewhere?
I guess this forum is not the place.
2011/3/14 Mark Tinguely <marktinguely at gmail.com>
> You are running out of physical memory, there is no swap backstore and the
> kernel is killing off other programs to claim memory.
> Compare the /etc/login.conf on both systems. I bet in the FreeBSD 6.3
> system, the memory limit is set to a limit (8M) and on the FreeBSD 8.1 it
> is much higher or is "unlimited". With a set memory limit, the "dd" is
> killed before the kernel starts killing off the other program.
> On 3/14/2011 6:41 AM, Mats Lindberg wrote:
> No - not from what I understand
> in the vmware it looks like a real disk device /dev/ad0s1e
> in the nfsroot'ed system I actually have 'of=/opt/something' which is
> definately to the nfs disk.
> 2011/3/14 Mark Tinguely <marktinguely at gmail.com>
>> On 3/14/2011 6:17 AM, Mats Lindberg wrote:
>>> I am migrating from FreeBSD 6.3 to FreeBSD 8.1 And I have noticed some,
>>> I think is, strange behaviour.
>>> In FreeBSD 6.3 when I do
>>>> swapoff -a
>>>> dd if=/dev/zero of=/tmp/whatever bs=1G count=1
>>> I get something like "out of memory - killed"
>>> In FreeBSD 8.1 doing the same - processes around start to die, e.g. all
>>> getty's are killed and finally devfs goes the same way.
>>> My target is diskless nfs mounted to a linux fileserver - hence no swap
>>> It does not seem to be relalted to the nfs root however - I get the same
>>> behaviour running FBSD-8.1 in a VMWARE server session.
>>> Is this a new 'feature' of FBSD or just a bug?
>>> Are there some sysctl's to set to 'really' turn of swapping.
>>> At one instance I also got a kernel panic saying 'page fault in kernel'
>>> I'm having a hard time to repeat just that.
>>> freebsd-hackers at freebsd.org mailing list
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>>> freebsd-hackers-unsubscribe at freebsd.org"
>>> Do you have /tmp mounted on a memory filesystem?
>> --Mark Tinguely
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