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

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Date:   Tue, 6 Dec 2016 08:58:34 +0800
From:   Boqun Feng <boqun.feng@...il.com>
To:     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

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.

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
> 

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