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To: Xueming Li <xuemingl@nvidia.com>
Cc: dev@dpdk.org, Viacheslav Ovsiienko <viacheslavo@nvidia.com>,
 Thomas Monjalon <thomas@monjalon.net>, Ferruh Yigit <ferruh.yigit@intel.com>
References: <20210727034204.20649-1-xuemingl@nvidia.com>
From: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Message-ID: <5909c370-666d-f36c-0456-abb9710011d5@oktetlabs.ru>
Date: Wed, 28 Jul 2021 10:56:40 +0300
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Subject: Re: [dpdk-dev] [RFC] ethdev: introduce shared Rx queue
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On 7/27/21 6:42 AM, Xueming Li wrote:
> In eth PMD driver model, each RX queue was pre-loaded with mbufs for
> saving incoming packets. When number of SF or VF scale out in a switch
> domain, the memory consumption became significant. Most important,
> polling all ports leads to high cache miss, high latency and low
> throughput.
> 
> To save memory and speed up, this patch introduces shared RX queue.
> Ports with same configuration in a switch domain could share RX queue
> set by specifying offloading flag RTE_ETH_RX_OFFLOAD_SHARED_RXQ. Polling
> a member port in shared RX queue receives packets for all member ports.
> Source port is identified by mbuf->port.
> 
> Queue number of ports in shared group should be identical. Queue index
> is 1:1 mapped in shared group.
> 
> Shared RX queue is supposed to be polled on same thread.
> 
> Multiple groups is supported by group ID.
> 
> Signed-off-by: Xueming Li <xuemingl@nvidia.com>

It looks like it could be useful to artificial benchmarks, but
absolutely useless for real life. SFs and VFs are used by VMs
(or containers?) to have its own part of HW. If so, SF or VF
Rx and Tx queues live in a VM and cannot be shared.

Sharing makes sense for representors, but it is not mentioned in
the description.