Messages in this thread | | | Date | Tue, 18 Jul 2017 10:36:17 -0400 | From | Keith Busch <> | Subject | Re: [PATCH] nvme: Acknowledge completion queue on each iteration |
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On Mon, Jul 17, 2017 at 07:07:00PM -0400, okaya@codeaurora.org wrote: > Maybe, I need to understand the design better. I was curious why completion > and submission queues were protected by a single lock causing lock > contention.
Ideally the queues are tied to CPUs, so you couldn't have one thread submitting to a particular queue-pair while another thread is reaping completions from it. Such a setup wouldn't get lock contention.
Some machines have so many CPUs, though, that sharing hardware queues is required. We've experimented with separate submission and completion locks for such cases, but I've never seen an improved performance as a result.
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