On Fri, Jul 01, 2016 at 08:21:21AM +0900, Byungchul Park wrote:
> On Thu, Jun 30, 2016 at 03:04:58PM +0200, Peter Zijlstra wrote:
> > On Mon, Jun 20, 2016 at 01:55:23PM +0900, Byungchul Park wrote:
> > > @@ -215,6 +219,11 @@ struct page {
> > > #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
> > > int _last_cpupid;
> > > #endif
> > > +
> > > +#ifdef CONFIG_LOCKDEP_PAGELOCK
> > > + struct lockdep_map map;
> > > + struct cross_lock xlock;
> > > +#endif
> > > }
> >
> > So that's 32+64=96 bytes (CONFIG_LOCK_STAT=n) added to struct page,
> > really!?
>
> Yes... I concerned it at first, but I thought it would be ok since
> CONFIG_LOCKDEP_PAGE is a debug feature. Anyway, I will try to reduce
> the size of struct cross_lock which is only thing I can do to reduce
> it, since we cannot avoid using lockdep_map if we want to make
> lock_page() participate in the lockdep play.
Please use page_ext instead. With boottime switch to enable.
This way we can have this compile-time debug option enabled on more
machines without unnecessary runtime overhead.
And, please, CC linux-mm next time.
--
Kirill A. Shutemov
