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From: Waiman Long <waiman.long@hpe.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Jason Low <jason.low2@hpe.com>,
	Ding Tianhong <dingtianhong@huawei.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	Will Deacon <Will.Deacon@arm.com>, Ingo Molnar <mingo@redhat.com>,
	Imre Deak <imre.deak@intel.com>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	Davidlohr Bueso <dave@stgolabs.net>,
	"Tim Chen" <tim.c.chen@linux.intel.com>,
	Terry Rudd <terry.rudd@hpe.com>,
	"Paul E. McKenney" <paulmck@us.ibm.com>,
	Jason Low <jason.low2@hp.com>
Subject: Re: [RFC][PATCH 1/3] locking/mutex: Rework mutex::owner
Date: Tue, 23 Aug 2016 16:17:54 -0400	[thread overview]
Message-ID: <57BCAF72.7020904@hpe.com> (raw)
In-Reply-To: <20160823124856.763266868@infradead.org>

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.

Cheers,
Longman

  parent reply	other threads:[~2016-08-23 20:53 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-23 12:46 [RFC][PATCH 0/3] locking/mutex: Rewrite basic mutex Peter Zijlstra
2016-08-23 12:46 ` [RFC][PATCH 1/3] locking/mutex: Rework mutex::owner Peter Zijlstra
2016-08-23 19:55   ` Waiman Long
2016-08-23 20:52     ` Tim Chen
2016-08-23 21:03       ` Peter Zijlstra
2016-08-23 21:09     ` Peter Zijlstra
2016-08-23 20:17   ` Waiman Long [this message]
2016-08-23 20:31     ` Peter Zijlstra
2016-08-24  9:56   ` Will Deacon
2016-08-24 15:34     ` Peter Zijlstra
2016-08-24 16:52       ` Peter Zijlstra
2016-08-24 16:54         ` Will Deacon
2016-08-23 12:46 ` [RFC][PATCH 2/3] locking/mutex: Allow MUTEX_SPIN_ON_OWNER when DEBUG_MUTEXES Peter Zijlstra
2016-08-23 12:46 ` [RFC][PATCH 3/3] locking/mutex: Add lock handoff to avoid starvation Peter Zijlstra
2016-08-23 12:56   ` Peter Zijlstra
     [not found]   ` <57BCA869.1050501@hpe.com>
2016-08-23 20:32     ` Peter Zijlstra
2016-08-24 19:50       ` Waiman Long
2016-08-25  8:11         ` Peter Zijlstra
2016-08-23 16:17 ` [RFC][PATCH 0/3] locking/mutex: Rewrite basic mutex Davidlohr Bueso
2016-08-23 16:35   ` Jason Low
2016-08-23 16:57     ` Peter Zijlstra
2016-08-23 19:36       ` Waiman Long
2016-08-23 20:41         ` Peter Zijlstra
2016-08-23 22:34           ` Waiman Long
2016-08-24  1:13     ` Jason Low
2016-08-25 12:32       ` Peter Zijlstra
2016-08-25 15:43       ` Peter Zijlstra
2016-08-25 16:33         ` Waiman Long
2016-08-25 16:35           ` Peter Zijlstra
2016-08-27 18:27             ` Ingo Molnar
2016-08-25 19:11         ` huang ying
2016-08-25 19:26           ` Peter Zijlstra
2016-08-23 18:53   ` Linus Torvalds
2016-08-23 20:34     ` Peter Zijlstra

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