netdev - Re: [RFC PATCH v2 02/11] netdev: implement netlink api to bind dma-buf to netdevice

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Message-ID: <20230821141659.5f0b71f7@kernel.org>
Date: Mon, 21 Aug 2023 14:16:59 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: David Ahern <dsahern@...nel.org>, Mina Almasry <almasrymina@...gle.com>,
 Praveen Kaligineedi <pkaligineedi@...gle.com>, netdev@...r.kernel.org, Eric
 Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Jesper
 Dangaard Brouer <hawk@...nel.org>, Ilias Apalodimas
 <ilias.apalodimas@...aro.org>, Magnus Karlsson <magnus.karlsson@...el.com>,
 sdf@...gle.com, Willem de Bruijn <willemb@...gle.com>, Kaiyuan Zhang
 <kaiyuanz@...gle.com>
Subject: Re: [RFC PATCH v2 02/11] netdev: implement netlink api to bind
 dma-buf to netdevice

On Sat, 19 Aug 2023 10:18:57 -0400 Willem de Bruijn wrote:
> Right. Many devices only allow bringing all queues down at the same time.
> 
> Once a descriptor is posted and the ring head is written, there is no
> way to retract that. Since waiting for the device to catch up is not
> acceptable, the only option is to bring down the queue, right? Which
> will imply bringing down the entire device on many devices. Not ideal,
> but acceptable short term, imho.
> 
> That may be an incentive for vendors to support per-queue
> start/stop/alloc/free. Maybe the ones that support RDMA already do?

Are you talking about HW devices, or virt? I thought most HW made 
in the last 10 years should be able to take down individual queues :o