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SubjectRe: [PATCH v8 10/10] pvqspinlock, x86: Enable qspinlock PV support for XEN
On 04/02/2014 10:39 AM, Konrad Rzeszutek Wilk wrote:
>> diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks
>> index a70fdeb..451e392 100644
>> --- a/kernel/Kconfig.locks
>> +++ b/kernel/Kconfig.locks
>> @@ -229,4 +229,4 @@ config ARCH_USE_QUEUE_SPINLOCK
>>
>> config QUEUE_SPINLOCK
>> def_bool y if ARCH_USE_QUEUE_SPINLOCK
>> - depends on SMP&& (!PARAVIRT_SPINLOCKS || !XEN)
>> + depends on SMP
> If I read this correctly that means you cannot select any more the old
> ticketlocks? As in, if you select CONFIG_PARAVIRT on X86 it will automatically
> select ARCH_USE_QUEUE_SPINLOCK which will then enable this by default?
>
> Should the 'def_bool' be selectable?

My initial qspinlock patch allows it to be selectable, but there was
comment that doing so would increase the testing matrix and so made it
less desirable. That was why I made it the default for 64-bit code which
are more likely to be used in large machines which benefit the most from
this patch. 32-bit kernel will still use the ticket lock.

-Longman


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