Re: ZFS deadlocks/memory accounting issues

On Mon, Mar 16, 2026 at 3:39 PM Garrett Wollman <wollman@bimajority.org> wrote:
>
> BTW, Alan, mail to your freebsd.org mailbox bounces because you
> forward to gmail.
>
> <<On Mon, 16 Mar 2026 15:29:00 -0600, Alan Somers <asomers@freebsd.org> said:
>
> > I don't know how to do it from ddb.  But if you dump a core file,
>
> None of our systems are set up for that.  They all have huge memory
> and pretty tiny swap partitions, and in any case, they don't panic,
> they just deadlock.  Or the OOM killer just shoots all user processes;
> these are nearly indistinguishable from a service provider's
> perspective.
>
> They're just NFS servers; they don't run anything else except what's
> necessary for monitoring and administration.
>
> -GAWollman

Pretty tiny swap partitions?  Maybe that's the problem.  I recall kib@
telling me that some amount of swap is essential, even when plenty of
RAM is available.  But I can't remember why.  So if you can't upgrade
those tiny swap partitions, then I suggest you install an SSD just for
use as a dump device.  I've done that sometimes.