Subject: Re: Consistent vnlock dead locks in low memory conditions
To: Stephen Jones <>
From: Manuel Bouyer <>
List: tech-net
Date: 06/22/2006 23:15:09
On Thu, Jun 22, 2006 at 01:36:14PM -0700, Stephen Jones wrote:
> On Jun 22, 2006, at 12:35 PM, Manuel Bouyer wrote:
> >Did you do some tuning ? Large buffer cache, or change uvm settings ?
> >A too high kern.maxvnodes can cause this, for example.
> What is considered two high?

Depends on RAM available, and other things I guess

> Would that really cause a deadlock?

in my experience, yes.

> Is  
> there
> a formula for determining what BUFCACHE or kern.maxvnodes set to?   
> What would
> be too low?  If the concern is that the BUFCACHE is too large or  
> kern.maxvnodes
> then how is that determined?  The default is 10055, is that too low?  
> why is it
> 10055?

If you didn't change the default value then it's probably OK.

> BUFCACHE I have set to 6 (%) in the kernel, can that be set  
> via sysctl as well?

Yes, it's vm.bufcache.

> I should also note I have vfs.nfs.iothreads set to 0 and have had it  
> that way for
> a couple of years now.

If it's a NFS server it doens't matter; this is for clients.

Manuel Bouyer <>
     NetBSD: 26 ans d'experience feront toujours la difference