File trees: the deeper, the weirder
matt at gsicomp.on.ca
Sun Oct 29 16:31:59 UTC 2006
[ Restoring some OP context.]
> On Sun, Oct 29, 2006 at 05:07:16PM +0300, Yar Tikhiy wrote:
> > As for the said program, it keeps its 1 Hz pace, mostly waiting on
> > "vlruwk". It's killable, after a delay. The system doesn't show ...
> > Weird, eh? Any ideas what's going on?
> I would guess that you need a new vnode to create the new file, but no
> vnodes are obvious candidates for freeing because they all have a child
> directory in use. Is there some sort of vnode clearing that goes on every
> second if we are short of vnodes?
See sys/vfs_subr.c, subroutine getnewvnode(). We call msleep() if we're
waiting on vnodes to be created (or recycled). And just look at the 'hz'
parameter passed to msleep()!
The calling process's mkdir() will end up waiting in getnewvnode() (in
"vlruwk" state) while the vnlru kernel thread does it's thing (which is to
Either the vnlru kernel thread has to work faster, or the caller has to
sleep less, in order to avoid this lock-step behaviour.
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