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Date: Thu, 29 May 2014 08:46:06 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com,
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Subject: Re: [RFC] Implement Batched (group) ticket lock
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On Wed, May 28, 2014 at 05:46:39PM +0530, Raghavendra K T wrote:
> In virtualized environment there are mainly three problems
> related to spinlocks that affect performance.
> 1. LHP (lock holder preemption)
> 2. Lock Waiter Preemption (LWP)
> 3. Starvation/fairness
> 
>  Though ticketlocks solve the fairness problem, it worsens LWP, LHP problems.
> pv-ticketlocks tried to address this. But we can further improve at the
> cost of relaxed fairness.

So I really hate the idea of having different locks for paravirt and
normal kernels.

And we're looking to move to that queued lock for normal kernels.