vm_thread_new: kstack allocation failed with many ZFS FS and NFSD

[Kris Kennaway]

Thomas Vogt wrote:
> Hi List(s)
> 
> I try to simulate real workload for our environment in my lab. The idea
> was to create 10k+ ZFS fs with several thousand files on each fs and
> then measure daily workload performance. Maybe 10k fs sounds silly but
> if you need individual quota for every user on a system, 5-10k fs are
> not unusual for ZFS
> 
> My script to cerate zfs fs
> #!/bin/sh
> i=0; while [ $i != 10000 ]; do zfs create tank/script$i; i=`expr $i +
> 1`; done
> 
> My script stopped after creating ~4850 FS with:
> vm_thread_new: kstack allocation failed
> vm_thread_new: kstack allocation failed
> vm_thread_new: kstack allocation failed
> vm_thread_new: kstack allocation failed
> vm_thread_new: kstack allocation failed
> vm_thread_new: kstack allocation failed

Your kernel has run out of memory.  If you cannot tune kmem_size further 
then it cannot handle this many ZFS filesystems.

Kris