kern.maxpipekva exceeded, please see tuning(7).

Josef Karthauser joe at
Wed Aug 4 03:57:23 PDT 2004

On Wed, Aug 04, 2004 at 10:52:12AM +0100, Dick Davies wrote:
> * Josef Karthauser <joe at> [0818 10:18]:
> > I've got a 5.2.x machine which has hung and is giving the message
> > 'kern.maxpipekva exceeded, please see tuning(7)' on the console
> > whenever anyone tries to open a tcp connect to it.  Does anyone
> > know what this tweakable is about and what might cause it to be
> > "exceeded"?  The machine has been running fine for 6 months.
> It's a typo, should be:
> root at eris samba3 # sysctl -a|grep kva
> kern.ipc.maxpipekva: 8359936
> kern.ipc.maxpipekvawired: 4177920
> kern.ipc.pipekva: 262144
> kern.ipc.pipekvawired: 0
> vfs.buffreekvacnt: 0
> - when I had this a oouple of weeks back (on 5.2 release) it was because
> I'd borked my make.conf so I effectively forkbombed the box everytime I tried
> to build a port .... O_o
> any chance you changed something similar in your networking?
> (maybe a loop in your NAT rules or something?)

The problem appears to be caused by a failing disk returning DMA
errors in swap space.  What probably happened is that the tcp
connections stacked up and blew the alloted space.

Josef Karthauser (joe at
FreeBSD (cvs meister, admin and hacker)
Physics Particle Theory (student)
================ An eclectic mix of fact and theory. =================
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