Re: [PATCH v5 1/6] locking/pvqspinlock: Unconditional PV kick with _Q_SLOW_VAL

From: Waiman Long
Date: Thu Aug 13 2015 - 22:07:27 EST

On 08/08/2015 02:02 AM, Peter Zijlstra wrote:
On Fri, Aug 07, 2015 at 11:17:56PM -0400, Waiman Long wrote:
If _Q_SLOW_VAL has been set, the vCPU state must have been vcpu_hashed.
The extra check at the end of __pv_queued_spin_unlock() is unnecessary
and so is removed.
This is half the patch it should be.

Because if the load is not needed, then the store is not either, and
then there's the comments to update.

Sorry for the late reply.

That is true. Setting state to vcpu_hashed in pv_wait_head() isn't really necessary. I kept it there for consistency sake as the state may be set to vcpu_hashed in pv_kick_node(). We can certainly take that out.

BTW, could you also review the other patches when you have time? I am coming to the LinuxCon/Plumbers next week. Hopefully, I can chat with you again.


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