Re: [PATCH v15 16/16] unfair qspinlock: a queue based unfair lock

From: Peter Zijlstra
Date: Thu Apr 09 2015 - 03:02:05 EST

On Wed, Apr 08, 2015 at 02:32:19PM -0400, Waiman Long wrote:
> For a virtual guest with the qspinlock patch, a simple unfair byte lock
> will be used if PV spinlock is not configured in or the hypervisor
> isn't either KVM or Xen. The byte lock works fine with small guest
> of just a few vCPUs. On a much larger guest, however, byte lock can
> have serious performance problem.

Who cares?

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