linux-kernel - Re: [PATCH v8 2/6] powerpc: pSeries/Kconfig: Add qspinlock build config

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Date:   Tue, 6 Dec 2016 10:12:56 +0800
From:   Pan Xinhui <xinhui@...ux.vnet.ibm.com>
To:     Boqun Feng <boqun.feng@...il.com>,
        Pan Xinhui <xinhui.pan@...ux.vnet.ibm.com>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        benh@...nel.crashing.org, paulus@...ba.org, mpe@...erman.id.au,
        peterz@...radead.org, mingo@...hat.com, paulmck@...ux.vnet.ibm.com,
        waiman.long@....com, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v8 2/6] powerpc: pSeries/Kconfig: Add qspinlock build
 config



在 2016/12/6 09:24, Pan Xinhui 写道:
>
>
> 在 2016/12/6 08:58, Boqun Feng 写道:
>> On Mon, Dec 05, 2016 at 10:19:22AM -0500, Pan Xinhui wrote:
>>> pSeries/powerNV will use qspinlock from now on.
>>>
>>> Signed-off-by: Pan Xinhui <xinhui.pan@...ux.vnet.ibm.com>
>>> ---
>>>  arch/powerpc/platforms/pseries/Kconfig | 8 ++++++++
>>>  1 file changed, 8 insertions(+)
>>>
>>> diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
>>> index bec90fb..8a87d06 100644
>>> --- a/arch/powerpc/platforms/pseries/Kconfig
>>> +++ b/arch/powerpc/platforms/pseries/Kconfig
>>
>> Why here? Not arch/powerpc/platforms/Kconfig?
>>
>>> @@ -23,6 +23,14 @@ config PPC_PSERIES
>>>      select PPC_DOORBELL
>>>      default y
>>>
>>> +config ARCH_USE_QUEUED_SPINLOCKS
>>> +    default y
>>> +    bool "Enable qspinlock"
>>
>> I think you just enable qspinlock by default for all PPC platforms. I
>> guess you need to put
>>
>>     depends on PPC_PSERIES || PPC_POWERNV
>>
>> here to achieve what you mean in you commit message.
>>
oh, yes, need depends on PPC_PSERIES || PPC_POWERNV.

> yes, another good way.
> I prefer to put it in pseries/Kconfig as same as pv-qspinlocks config.
> when we build nv, it still include pSeries's config anyway.
>
> thanks
> xinhui
>
>> Regards,
>> Boqun
>>
>>> +    help
>>> +      Enabling this option will let kernel use qspinlock which is a kind of
>>> +      fairlock.  It has shown a good performance improvement on x86 and also ppc
>>> +      especially in high contention cases.
>>> +
>>>  config PPC_SPLPAR
>>>      depends on PPC_PSERIES
>>>      bool "Support for shared-processor logical partitions"
>>> --
>>> 2.4.11
>>>