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Date: Tue, 16 Aug 2016 10:37:15 +0800
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Rich Lane <rich.lane@bigswitch.com>
Cc: dev@dpdk.org, Huawei Xie <huawei.xie@intel.com>
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Subject: Re: [dpdk-dev] [PATCH] vhost: add back support for concurrent
	enqueue
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On Mon, Aug 15, 2016 at 01:00:24PM -0700, Rich Lane wrote:
> Concurrent enqueue is an important performance optimization when the number
> of cores used for switching is different than the number of vhost queues.
> I've observed a 20% performance improvement compared to a strategy that
> binds queues to cores.
> 
> The atomic cmpset is only executed when the application calls
> rte_vhost_enqueue_burst_mp. Benchmarks show no performance impact
> when not using concurrent enqueue.
> 
> Mergeable RX buffers aren't supported by concurrent enqueue to minimize
> code complexity.

I think that would break things when Mergeable rx is enabled (which is
actually enabled by default).

Besides that, as mentioned in the last week f2f talk, do you think adding
a new flag RTE_VHOST_USER_CONCURRENT_ENQUEUE (for rte_vhost_driver_register())
__might__ be a better idea? That could save us a API, to which I don't object
though.

	--yliu