Date: Tue, 11 Nov 2003 11:15:24 +1030 From: Alex Wilkinson <alex.wilkinson@dsto.defence.gov.au> To: Bruce Evans <bde@zeta.org.au> Cc: current@freebsd.org Subject: Re: erroneous message from locked-up machine Message-ID: <20031111004523.GE14579@squirm.dsto.defence.gov.au> In-Reply-To: <20031111042518.I857@gamplex.bde.org> References: <20031110164513.GA828@bewilderbeast.blackhelicopters.org> <20031111042518.I857@gamplex.bde.org>
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Can someone please elaborate on the acronym KVA ?
$ sysctl -d kern.ipc.maxpipekva
kern.ipc.maxpipekva: Pipe KVA limit
This doesn't tell me enough.
- aW
On Tue, Nov 11, 2003 at 04:46:47AM +1100, Bruce Evans wrote:
> > I came in to work today to find one of my -current machines unable to
> > open a pipe. (This probably had a lot to do with the spamd that went
> > stark raving nutters overnight, but that's a separate problem.) A
> > power cycle fixed the problem, but /var/log/messages was filled with:
> >
> > Nov 10 11:05:44 bewilderbeast kernel: kern.maxpipekva exceeded, please see tuning(7).
> >
> > Interesting.
> >
> > bewilderbeast~;sysctl kern.maxpipekva
> > sysctl: unknown oid 'kern.maxpipekva'
> > bewilderbeast~;
>
> The following patch fixes this and some nearby style bugs:
> - source style bug: line too line
> - output style bugs: comma splice, verboseness (helps make the source line
> too long), and kernel message terminated with a ".".
>
> %%%
> Index: sys_pipe.c
> ===================================================================
> RCS file: /home/ncvs/src/sys/kern/sys_pipe.c,v
> retrieving revision 1.158
> diff -u -2 -r1.158 sys_pipe.c
> --- sys_pipe.c 9 Nov 2003 09:17:24 -0000 1.158
> +++ sys_pipe.c 10 Nov 2003 17:21:47 -0000
> @@ -331,5 +331,5 @@
> if (error != KERN_SUCCESS) {
> if (ppsratecheck(&lastfail, &curfail, 1))
> - printf("kern.maxpipekva exceeded, please see tuning(7).\n");
> + printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
> return (ENOMEM);
> }
> %%%
>
> > And tuning(7) doesn't mention this, either.
> >
> > Is this just work-in-progress, or did someone forget to commit something?
>
> Seems like tuning pipe kva is completely absent in tuning(7) (so the above
> message can be shortened further). You can tune kva generally as documented
> there, but the pipe limit is separate.
>
> > PS: Lesson of the day: no pipe KVA, no su. Great fun on remote
> > machines! :-)
>
> It's interesting that su was the point of failure. It uses a pipe hack
> for IPC. Otherwise it doesn't use pipes, at least direectly. It
> shouldn't need to use the pipe hack. My version uses signals instead.
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