On Tue, Aug 23, 2016 at 04:17:54PM -0400, Waiman Long wrote:
> On 08/23/2016 08:46 AM, Peter Zijlstra wrote:
> > /*
> > * Simple, straightforward mutexes with strict semantics:
> >@@ -48,13 +49,9 @@
> > * locks and tasks (and only those tasks)
> > */
> > struct mutex {
> >- /* 1: unlocked, 0: locked, negative: locked, possible waiters */
> >- atomic_t count;
> >+ atomic_long_t owner;
> > spinlock_t wait_lock;
> > struct list_head wait_list;
> >-#if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_MUTEX_SPIN_ON_OWNER)
> >- struct task_struct *owner;
> >-#endif
> > #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
> > struct optimistic_spin_queue osq; /* Spinner MCS lock */
> > #endif
>
> I think you should put the wait_lock and osq next to each other to save 8
> bytes in space on 64-bit machines.
Right you are.. didn't get around to looking at layout yet. Just barely
got it to compile and boot :-)
