linux-kernel - Re: [PATCH] locking/osq: Drop the overload of osq lock

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Message-Id: <90D0C23D-65D5-40A8-89F1-4D02506A9CBC@linux.vnet.ibm.com>
Date:	Sun, 26 Jun 2016 01:27:51 +0800
From:	panxinhui <xinhui@...ux.vnet.ibm.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	panxinhui <xinhui@...ux.vnet.ibm.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Pan Xinhui <xinhui.pan@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, mingo@...hat.com, dave@...olabs.net,
	will.deacon@....com, Waiman.Long@....com, benh@...nel.crashing.org
Subject: Re: [PATCH] locking/osq: Drop the overload of osq lock


> 在 2016年6月26日，00:13，Peter Zijlstra <peterz@...radead.org> 写道：
> 
> On Sat, Jun 25, 2016 at 06:09:22PM +0200, Peter Zijlstra wrote:
>> That works here, but it would not work for the need_resched() in
>> mutex_spin_on_owner() and mutex_optimistic_spin() which need equal
>> treatment.
>> 
>> Because those too we want to limit.
>> 
>> The count thing, while a little more cumbersome, is more widely
>> applicable than just the one OSQ case where we happen to have a cpu
>> number.
> 
> Although I suppose that mutex_spin_on_owner() (and with that the rsem
> variant) could use task_cpu(lock->owner) once we've established that the
> owner pointer is still valid.
> 
> 
yes, What I am going to fix next is these XXX_spin_on_owner, including  mutex_spin_on_owner, rwsem_spin_on_owner ….

by the way I still think mutex_unlock has a big overload too.