Re: vnlur_proc lockups under high disk I/O

[Gary Allan <dragonfly@xxxxxxxxxxxxxxx>]

Matthew Dillon wrote:
>      Gary, thanks for the cores!  They helped me track the problem down.
>
>      It turns out to be a fairly simple bug in the kernel.  Basically what
>      is going on here is that the vnode recycler is not allowed to recycle
>      'internal' directory nodes in the namecache topology.  i.e. if the
>      path A/B/C/D is cached, then the recycler is not allowed to remove A, B,
>      or C.  The recycler checks this condition by checking the vnode's
>      v_holdcnt.
>
>      Unfortunately, it turns out that buffer cache buffers also bump
>      v_holdcnt, not just the namecache.  This was preventing the recycler
>      from recycling vnodes related to small files (e.g. the 'Root'
>      and 'Entries' found all over a cvs checkout of src) and causing your
>      lockup. 
>
>      I believe this patch will solve the problem.   Please try it out
>      and report back to the list.  Note that I have added some debugging
>      printfs (which will not be in the final commit).
>
> 						-Matt

I've automated the extraction of the archive and it's been running for 2 
hours without problems. I've also stressed file creation as much as I 
can and all seems well.

It probably doesn't make a difference but after the tests I noticed that 
debug.numvnodes > kern.maxvnodes.

kern.maxvnodes: 16565
kern.minvnodes: 4141
debug.numvnodes: 16590
debug.freevnodes: 7550
debug.wantfreevnodes: 25

Thanks for the quick response.

Regards

Gary