Re: [RFC PATCH v2] Implement Batched (group) ticket lock
From: Raghavendra K T
Date: Tue Jul 01 2014 - 05:47:45 EST
On 07/01/2014 01:35 PM, Peter Zijlstra wrote:
On Sat, Jun 28, 2014 at 02:47:04PM +0530, Raghavendra K T wrote:
In virtualized environment there are mainly three problems
related to spinlocks that affects performance.
1. LHP (lock holder preemption)
2. Lock Waiter Preemption (LWP)
3. Starvation/fairness
Though Ticketlocks solve fairness problem it worsens LWP, LHP problems. Though
pv-ticketlocks tried to address these problems we can further improve at the
cost of relaxed fairness. The following patch tries to achieve that by grouping
(batched) ticketlocks.
And here I stop reading and ignore this patch, right?
Why should I look at this?
For baremetal we continue to have 'fully fair ticketlock' with this
patch series.
Good thing about the patch is we do have upper bound on starvation and
at the same time we solve Lock Waiter Preemption horror of strict
serialization of ticketlocks in guest and combine definite advantages
of unfair locks for guest.
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