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Date: Wed, 3 Feb 2016 11:24:58 -0800
From: Davidlohr Bueso <dave@stgolabs.net>
To: Ding Tianhong <dingtianhong@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Waiman Long <waiman.long@hpe.com>,
        Jason Low <jason.low2@hp.com>, Ingo Molnar <mingo@redhat.com>,
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        Linus Torvalds <torvalds@linux-foundation.org>,
        "Paul E. McKenney" <paulmck@us.ibm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Will Deacon <Will.Deacon@arm.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Waiman Long <Waiman.Long@hp.com>
Subject: Re: [PATCH] locking/mutex: Avoid spinner vs waiter starvation
Message-ID: <20160203192458.GA26475@linux-uzut.site>
References: <20160122105312.GQ6357@twins.programming.kicks-ass.net>
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 <20160122110653.GF6375@twins.programming.kicks-ass.net>
 <56A235DC.2060900@hpe.com>
 <56A48566.9040206@huawei.com>
 <20160129095347.GA6356@twins.programming.kicks-ass.net>
 <56AC0F74.2040808@huawei.com>
 <20160201100824.GO6357@twins.programming.kicks-ass.net>
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On Wed, 03 Feb 2016, Ding Tianhong wrote:

>Agree, but this patch is going to help the waiter in the wait list to get the lock, your scene probability looks more
>too low and I don't think it is a problem.

Sure, I was in fact implying its not the end of the world,
although it will be interesting to see the impact on different
(non pathological) workloads, even if it only affects a single
waiter. Also, technically this issue can also affect rwsems if
only using writers, but that's obviously pretty idiotic, so I
wouldn't worry about it.

Thanks,
Davidlohr