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From: Cornelia Huck <cohuck@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: Dongli Zhang <dongli.zhang@oracle.com>,
	mst@redhat.com, virtualization@lists.linux-foundation.org,
	linux-block@vger.kernel.org, axboe@kernel.dk,
	linux-kernel@vger.kernel.org
Subject: Re: virtio-blk: should num_vqs be limited by num_possible_cpus()?
Date: Fri, 15 Mar 2019 13:41:12 +0100	[thread overview]
Message-ID: <20190315134112.7d63348c.cohuck@redhat.com> (raw)
In-Reply-To: <537e6420-8994-43d6-1d4d-ccb6e0fafa0b@redhat.com>

On Fri, 15 Mar 2019 12:50:11 +0800
Jason Wang <jasowang@redhat.com> wrote:

> Or something like I proposed several years ago? 
> https://do-db2.lkml.org/lkml/2014/12/25/169
> 
> 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
possible.

  reply	other threads:[~2019-03-15 12:41 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-12 17:22 virtio-blk: should num_vqs be limited by num_possible_cpus()? Dongli Zhang
2019-03-12 17:33 ` Cornelia Huck
2019-03-13  3:26   ` Dongli Zhang
2019-03-13  9:39     ` Cornelia Huck
2019-03-14  6:12       ` Dongli Zhang
2019-03-14 12:13         ` Cornelia Huck
2019-03-14 16:08           ` Dongli Zhang
2019-03-15  4:50         ` Jason Wang
2019-03-15 12:41           ` Cornelia Huck [this message]
2019-03-18  7:47             ` Jason Wang
2019-03-19  2:22               ` Dongli Zhang
2019-03-20 12:53                 ` Jason Wang
2019-03-21  2:14                   ` Dongli Zhang
2019-03-21 15:57                   ` Stefan Hajnoczi
2019-03-14 12:32 ` Michael S. Tsirkin
2019-03-14 15:36   ` Dongli Zhang

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