vm_thread_new: kstack allocation failed with many ZFS FS and
kostikbel at gmail.com
Tue Mar 11 02:48:34 PDT 2008
On Mon, Mar 10, 2008 at 09:24:55PM -0700, Kip Macy wrote:
> On Mon, Mar 10, 2008 at 6:13 PM, Zaphod Beeblebrox <zbeeble at gmail.com> wrote:
> > On Mon, Mar 10, 2008 at 8:30 PM, Kris Kennaway <kris at freebsd.org> wrote:
> > > Your kernel has run out of memory. If you cannot tune kmem_size further
> > > then it cannot handle this many ZFS filesystems.
> > Roughly how much kernel memory does a filesystem use (even if inactive) ---
> > or did you really mean something like too many pools?
> > The ZFS documentation encourages creating filesystems for everything. I
> > think my (rather beafy) laptop has 20 filesystems now for various tasks ---
> > but I didn't realize there was a non-trivial cost (that is: a cost beyond
> > the mount structure, root vnodes and whatnot)...
> There may be kernel threads created for each file system. One way to
> look at it is that a process isn't that expensive, but FreeBSD
> probably couldn't cope very well with 5000 processes.
On the usual modern i386 hardware with usual load we easily handle
~30000 threads, with the top coming at around 50000 threads. The most
limiting factor, from my POV, is the kernel address space, since each
thread takes 3 pages for the kernel stack.
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