Re: high load, no bottleneck

[Matthias Scheler <tron%zhadum.org.uk@localhost>]

On Tue, Sep 17, 2013 at 02:30:56PM +0000, Emmanuel Dreyfus wrote:
> On Tue, Sep 17, 2013 at 12:54:59PM +0000, Emmanuel Dreyfus wrote:
> > I have a NFS server that exhibit a high load (20-30) when supporting
> > about 30 clients, while there is no apparent bottleneck: low disck 
> > activity, CPU idle most of the time, plenty of available RAM.
> > 
> > Of course service is crapy, with many timouts. Any hint of what can be
> > going on?
> 
> I found the bottleneck. ps does not show it because it happens within
> the differen threads of nfsd.  DDB tells me that almost all nfsd threads 
> are waiting on tstile with this backtrace:
> 
> turnstile_block
> rw_vector_enter
> genfs_lock
> VOP_LOCK
> vn_lock
> vget
> ufs_ihashget
> ffs_vget
> ufs_fhtovp
> VFS_FHTOVP
> nfsrv_fhtovp
> nfsrv_write
> nfssvc_nfsd
> sys_nfssvc

What version of NetBSD is this? Does the local file-system on the
NetBSD NFS servers use WAPBL?

        Kind regards

-- 
Matthias Scheler                                  http://zhadum.org.uk/