From: Pan Xinhui <xinhui@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>, Waiman Long <Waiman.Long@hpe.com>
Cc: Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org,
Scott J Norton <scott.norton@hpe.com>,
Douglas Hatch <doug.hatch@hpe.com>
Subject: Re: [PATCH] locking/pvqspinlock: Add lock holder CPU argument to pv_wait()
Date: Thu, 14 Apr 2016 16:39:56 +0800 [thread overview]
Message-ID: <570F575C.8010400@linux.vnet.ibm.com> (raw)
In-Reply-To: <20160414002135.GP2906@worktop>
On 2016年04月14日 08:21, Peter Zijlstra wrote:
> On Wed, Apr 13, 2016 at 04:59:20PM -0400, Waiman Long wrote:
>> Pan Xinhui was asking for a lock holder cpu argument in pv_wait()
>> to help the porting of pvqspinlock to PPC. The new argument will can
>> potentially help hypervisor expediate the execution of the critical
>> section so that the lock holder vCPU can release the lock sooner.
>>
>> This patch does just that by storing the previous node vCPU number.
>> In pv_wait_head_or_lock(), pv_wait() will be called with that vCPU
>> number as it is likely to be the lock holder. In pv_wait_node(),
>> -1 will be passed to pv_wait() instead to indicate that it doesn't
>> know what the current lock holder is.
>
> Without knowing why he needs this, it is very hard to tell if this will
> suffice.
>
> Xinhui, what do you need the extra argument for?
>
We the could give current vcpu's slice to that vcpu. The lock holder has more slice to run, the lock might be unlocked earlier. :)
next prev parent reply other threads:[~2016-04-14 8:41 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-13 20:59 [PATCH] locking/pvqspinlock: Add lock holder CPU argument to pv_wait() Waiman Long
2016-04-14 0:21 ` Peter Zijlstra
2016-04-14 1:59 ` Waiman Long
2016-04-14 8:39 ` Pan Xinhui [this message]
2016-04-14 9:36 ` Pan Xinhui
2016-04-14 14:34 ` Pan Xinhui
2016-04-14 18:47 ` Waiman Long
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