Re: lock_stat &rq->lock/1 class name meaning

[Juri Lelli]

Thanks!

On 05/12/2011 12:57 PM, Yong Zhang wrote:
> On Wed, May 11, 2011 at 06:26:10PM +0200, Juri Lelli wrote:
> > Hi,
> > I'm trying to collect contention statistics through /proc/lock_stat
> > about scheduler data structures.
> >
> > What I obtain if a do "cat /proc/lock_stat" is something like:
> > ...
> > &rq->lock:         13128          13128           0.43
> > [...]
> >
> > I guess the first one is about the per-rq (per-CPU) spinlock, but
> > what about the second? What the "/1" stands for?
>
> It is also rq but it's subclass is 1.
>
> Take a look at raw_spin_lock_nested(&this_rq->lock, SINGLE_DEPTH_NESTING);
> in _double_lock_balance()

Ok, I've put more light on this also looking at lockdep.h comments and 
lockdep-design documentation.

Since I'm probably not the only one having troubles undestanding 
lock_stat output, maybe could be useful to add something on this inside 
lockstat documentation (I can try to do this). What you think?

	Juri
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/