linux-kernel - Re: [PATCH 3/6] locking/rwsem: Set lock ownership ASAP

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Date:	Tue, 27 Jan 2015 11:18:24 -0800
From:	Davidlohr Bueso <dave@...olabs.net>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Jason Low <jason.low2@...com>,
	Michel Lespinasse <walken@...gle.com>,
	Tim Chen <tim.c.chen@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/6] locking/rwsem: Set lock ownership ASAP

On Tue, 2015-01-27 at 18:10 +0100, Peter Zijlstra wrote:
> This is the thing I suggested
> lkml.kernel.org/r/20150108103708.GE29390@...ns.programming.kicks-ass.net
> there right?

Yeah.

> Do you have numbers for how much this gained?

This is more of a correctness patch, nothing really tangible for
performance -- although I did note a 5% tp increase as that particular
workload, as pounds on the osq so we have to wait for the node->next
pointer. Otherwise, the window between when we set the lock is taken and
owner is set is very small.

Thanks,
Davidlohr


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