Linux Virtualization - May 2014 - [PATCH v10 08/19] qspinlock: Make a new qnode structure to support virtualization

On Wed, May 07, 2014 at 11:01:36AM -0400, Waiman Long
wrote:
>  /*
> + * To have additional features for better virtualization support, it is
> + * necessary to store additional data in the queue node structure. So
> + * a new queue node structure will have to be defined and used here.
> + */
> +struct qnode {
> +	struct mcs_spinlock mcs;
> +};
You can ditch this entire patch; its pointless, just add a new
DEFINE_PER_CPU for the para-virt muck.

On 05/08/2014 03:04 PM, Peter Zijlstra wrote:
> On Wed, May 07, 2014 at 11:01:36AM -0400, Waiman Long wrote:
>>   /*
>> + * To have additional features for better virtualization support, it
is
>> + * necessary to store additional data in the queue node structure. So
>> + * a new queue node structure will have to be defined and used here.
>> + */
>> +struct qnode {
>> +	struct mcs_spinlock mcs;
>> +};
> You can ditch this entire patch; its pointless, just add a new
> DEFINE_PER_CPU for the para-virt muck.
Yes, I can certainly merge it to the next one in the series. I break it 
out to make each individual patch smaller, more single-purpose and 
easier to review.

-Longman

On Fri, May 09, 2014 at 09:08:56PM -0400, Waiman Long
wrote:
> On 05/08/2014 03:04 PM, Peter Zijlstra wrote:
> >On Wed, May 07, 2014 at 11:01:36AM -0400, Waiman Long wrote:
> >>  /*
> >>+ * To have additional features for better virtualization support,
it is
> >>+ * necessary to store additional data in the queue node structure.
So
> >>+ * a new queue node structure will have to be defined and used
here.
> >>+ */
> >>+struct qnode {
> >>+	struct mcs_spinlock mcs;
> >>+};
> >You can ditch this entire patch; its pointless, just add a new
> >DEFINE_PER_CPU for the para-virt muck.
> 
> Yes, I can certainly merge it to the next one in the series. I break it out
> to make each individual patch smaller, more single-purpose and easier to
> review.
No, don't merge it, _drop_ it. Wrapping things in a struct generates a
ton of pointless change.

Put the new data in a new DEFINE_PER_CPU and leave the existing code as
is.
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