Re: [NFS] "used greatest stack depth: n bytes left" messages

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, Sep 12, 2007 at 02:54:08PM +0200, Le Rouzic wrote:
>   CONFIG_DEBUG_STACK_USAGE was already set in my previous kernel configuration
>   but those messages are new  but like you wrote more for debug warning.
>   Nevertheless the question was more to know if they mean some degradation
>   happening. So far, it looks not.

Right, it doesn't necessarily mean anything, it's just telling you the
number of bytes that weren't used on the stack.  If you've got thousands
of bytes left:

> >>Sep 11 12:22:40 frec kernel: loadkeys used greatest stack depth: 4568
> >>bytes left
> >>Sep 11 12:22:40 frec kernel: rc.sysinit used greatest stack depth: 4448
> >>bytes left
> >>Sep 11 12:22:40 frec kernel: readahead used greatest stack depth: 4264
> >>bytes left
> >>Sep 11 13:38:36 frec kernel: mount.nfs4 used greatest stack depth: 4088
> >>bytes left
> >>Sep 11 17:12:08 frec kernel: mount.nfs4 used greatest stack depth: 3512
> >>bytes left

then nothing's coming anywhere near overflowing its stack, so that's
good.  (But do you know what stack size your kernel is using?  I guess
it's >4k, so probably 8k, suggesting some of these processes are using
over 4k, which seems like a lot.)

--b.