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

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Date:   Tue, 6 Dec 2016 09:24:08 +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 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.
>
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
>>