linux-kernel - Re: [PATCH v2 1/4] locking/mutex: Add waiter parameter to mutex_optimistic

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Message-ID: <20160212220902.GB16417@linux-uzut.site>
Date:	Fri, 12 Feb 2016 14:09:02 -0800
From:	Davidlohr Bueso <dave@...olabs.net>
To:	Waiman Long <Waiman.Long@....com>
Cc:	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ding Tianhong <dingtianhong@...wei.com>,
	Jason Low <jason.low2@....com>,
	"Paul E. McKenney" <paulmck@...ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Will Deacon <Will.Deacon@....com>,
	Tim Chen <tim.c.chen@...ux.intel.com>,
	Waiman Long <Waiman.Long@...com>
Subject: Re: [PATCH v2 1/4] locking/mutex: Add waiter parameter to
 mutex_optimistic_spin()

On Fri, 12 Feb 2016, Davidlohr Bueso wrote:

>This can be a really hot path, could we get rid of the waiter check and just
>introduce mutex_tro_to_acquire_waiter() or such and set the counter to -1 there?

Ah nm, I just realized why you do this :) For a second I thought that you called into
this directly from __mutex_lock_common.