Messages in this thread | | | Date | Tue, 23 Aug 2016 22:31:03 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC][PATCH 1/3] locking/mutex: Rework mutex::owner |
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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 :-)
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