On Sep 17, 2013, at 5:39 PM, Emmanuel Dreyfus <m...@netbsd.org> wrote:
> I was suggested this should be better posted on tech-kern. It happened > on NetBSD-6.0, and I tried to upgrade the kernel to -current, with the > same result. > > 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 are your clients doing? Which vnode(s) are your nfsd threads waiting on (first arg to vn_lock)? -- J. Hannken-Illjes - hann...@eis.cs.tu-bs.de - TU Braunschweig (Germany)
