ZFS and deadlock with {nullfs,NFS}

[John Nielsen]

On Wednesday 20 June 2007 03:56:13 pm Dan Mack wrote:
> On Wed, 20 Jun 2007, John Nielsen wrote:
> > On Wednesday 20 June 2007 12:30:23 pm Dan Mack wrote:
> >> On Wed, 20 Jun 2007, Kris Kennaway wrote:
> >>
> >> <snip>
> >>
> >>> 404 at the moment, but look for processes involving zil* in the
> >>> backtrace.  I had to disable zil (vfs.zfs.zil_disable=1 tunable) to
> >>> prevent low-memory deadlocks on my machines.  Since then it's been
> >>> fine.
> >>>
> >>> You may also wish to use my patches (see the archives) to improve
> >>> performance and low-memory behaviour.
> >>>
> >>> Kris
> >>
> >> Does someone have these recommended sysctls embodied in an example
> >> /boot/loader.conf yet?   Here is mine, does it look reasonable to keep
> >> ZFS from running into the kmem_ memory panics?  I have no idea if I
> >> found all of your recommendations so it would be nice if they were
> >> summarized in one place.
> >>
> >>   |  # /boot/loader.conf  i386 / 1GB memory / SMP
> >>   |  kern.maxvnodes="50000"
> >
> > Note that kern.maxvnodes has to be set in /etc/sysctl.conf to have any
> > effect.
> >
> > JN
>
> FWIW ... I'm still experiencing panics; this time with when running cvsup
> to update /usr/ports:
>
> borg# grep -i Panic /var/crash/info*
> /var/crash/info.0:  Panic String: kmem_malloc(16384): kmem_map too small:
> 268419072 total allocated /var/crash/info.1:  Panic String:
> kmem_malloc(131072): kmem_map too small: 266354688 total allocated
> /var/crash/info.2:  Panic String: kmem_malloc(4096): kmem_map too small:
> 268435456 total allocated /var/crash/info.3:  Panic String:
> kmem_malloc(28672): kmem_map too small: 268435456 total allocated
>
>
> Anyone ideas on other tunables that might keep the system running?  I'm
> not too concerned about performance.   Otherwise I'll have to go spend
> some money on an AMD64 mainboard, memory, and cpu :-(

The only tunable I had that you didn't was this one:

vfs.zfs.arc_max="83886080"

FWIW, my i386 system has 1.5GB RAM. More RAM might help, and/or you probably 
still need to do some balancing (read: fiddling) with the tunables you're 
already adjusting.

JN