system slowdown - vnode related

[Marc G. Fournier]

Ack, only 512Meg of memory? :(  k, now you are beyond me on this one ...
I'm running 4Gig on our server, with 2Gig allocated to kernel memory ...

only thing I can suggest is try slowly incrementing up your maxvnodes and
see if that helps, but, I'm not sure where your upper threshhold is with
512Meg of RAM ...

On Mon, 26 May 2003, Mike Harding wrote:

> On my sytem, with 512 meg of memory, I have the following (default)
> vnode related values:
>
> bash-2.05b$ sysctl -a | grep vnode
> kern.maxvnodes: 36079
> kern.minvnodes: 9019
> vm.stats.vm.v_vnodein: 140817
> vm.stats.vm.v_vnodeout: 0
> vm.stats.vm.v_vnodepgsin: 543264
> vm.stats.vm.v_vnodepgsout: 0
> debug.sizeof.vnode: 168
> debug.numvnodes: 33711
> debug.wantfreevnodes: 25
> debug.freevnodes: 5823
>
> ...is this really low?  Is this something that should go into
> tuning(7)?  I searched on google and found basically nothing related to
> adjust vnodes - although I am admittedly flogging the system - I have
> leafnode+ running, a mirrored CVS tree, an experimental CVS tree,
> mount_union'd /usr/ports in a jaile, and so on.  Damn those $1 a
> gigabyte drives!
>
> On Mon, 2003-05-26 at 09:12, Marc G. Fournier wrote:
> > On Mon, 26 May 2003, Mike Harding wrote:
> >
> > > Er - are any changes made to RELENG_4_8 that aren't made to RELENG_4?  I
> > > thought it was the other way around - that 4_8 only got _some_ of the
> > > changes to RELENG_4...
> >
> > Ack, my fault ... sorry, wasn't thinking :(  RELENG_4 is correct ... I
> > should have confirmed my settings before blathering on ...
> >
> > One of the scripts I used extensively while debugging this ... a quite
> > simple one .. was:
> >
> > #!/bin/tcsh
> > while ( 1 )
> >   echo `sysctl debug.numvnodes` - `sysctl debug.freevnodes` - `sysctl debug.vnlru_nowhere` - `ps auxl | grep vnlru | grep -v grep | awk '{print $20}'`
> >   sleep 10
> > end
> >
> > which outputs this:
> >
> > debug.numvnodes: 463421 - debug.freevnodes: 220349 - debug.vnlru_nowhere: 3 - vlruwt
> >
> > I have my maxvnodes set to 512k right now ... now, when the server "hung",
> > the output would look something like (this would be with 'default' vnodes):
> >
> > debug.numvnodes: 199252 - debug.freevnodes: 23 - debug.vnlru_nowhere: 12 - vlrup
> >
> > with the critical bit being the vlruwt -> vlrup change ...
> >
> > with unionfs, you are using two vnodes per file, instead of one in
> > non-union mode, which is why I went to 512k vs the default of ~256k vnodes
> > ... it doesn't *fix* the problem, it only reduces its occurance ...
>
>