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SubjectRe: [PATCH 3/7] locking/pvqspinlock: Implement wait-early for overcommitted guest
On 07/13/2015 03:50 PM, Davidlohr Bueso wrote:
> On Sat, 2015-07-11 at 16:36 -0400, Waiman Long wrote:
>> /*
>> + * Queued Spinlock Spin Thresholds
>> + * -------------------------------
>> + * Because of the cacheline contention effect of the ticket spinlock, the
>> + * same spin threshold for queued spinlock will run a bit faster. So we set
>> + * a slight larger threshold for the queue head (1.25X) while the other queue
>> + * nodes will keep the same threshold.
> How did you come to 1.25x? These sort of magic numbers scare me.
>

Yes, this is kind of arbitrary. I am going to get rid of it in the v2 patch.

Cheers,
Longman


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