linux-kernel - Re: [RFC 1/2] virtio_net: timeout control virtqueue commands

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Message-ID: <20251016014328-mutt-send-email-mst@kernel.org>
Date: Thu, 16 Oct 2025 01:45:28 -0400
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Jason Wang <jasowang@...hat.com>
Cc: Eugenio Perez Martin <eperezma@...hat.com>,
	Maxime Coquelin <mcoqueli@...hat.com>,
	Yongji Xie <xieyongji@...edance.com>,
	virtualization@...ts.linux.dev, linux-kernel@...r.kernel.org,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Dragos Tatulea DE <dtatulea@...dia.com>
Subject: Re: [RFC 1/2] virtio_net: timeout control virtqueue commands

On Thu, Oct 16, 2025 at 01:39:58PM +0800, Jason Wang wrote:
> > >
> > > Not exactly bufferize, record.  E.g. we do not need to send
> > > 100 messages to enable/disable promisc mode - together they
> > > have no effect.
> 
> Note that there's a case that multiple commands need to be sent, e.g
> set rx mode. And assuming not all the commands are the best effort,
> kernel VDUSE still needs to wait for the usersapce at least for a
> while.

Not wait, record. Generate 1st command, after userspace consumed it -
generate and send second command and so on.
But for each bit of data, at most one command has to be sent,
we do not care if guest tweaked rx mode 3 times, we only care about
the latest state.

-- 
MST