Re: virtio-blk: should num_vqs be limited by num_possible_cpus()?

From: Jason Wang
Date: Mon Mar 18 2019 - 03:47:35 EST

On 2019/3/15 äå8:41, Cornelia Huck wrote:
On Fri, 15 Mar 2019 12:50:11 +0800
Jason Wang <jasowang@xxxxxxxxxx> wrote:

Or something like I proposed several years ago?

Btw, for virtio-net, I think we actually want to go for having a maximum
number of supported queues like what hardware did. This would be useful
for e.g cpu hotplug or XDP (requires per cpu TX queue). But the current
vector allocation doesn't support this which will results all virtqueues
to share a single vector. We may indeed need more flexible policy here.
I think it should be possible for the driver to give the transport
hints how to set up their queues/interrupt structures. (The driver
probably knows best about its requirements.) Perhaps whether a queue is
high or low frequency, or whether it should be low latency, or even
whether two queues could share a notification mechanism without
drawbacks. It's up to the transport to make use of that information, if

Exactly and it was what the above series tried to do by providing hints of e.g which queues want to share a notification.