linux-kernel - Re: [PATCH v1 0/2] virtio-mmio: support multiple interrupt vectors

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Date:   Fri, 19 Jul 2019 11:14:28 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Fei Li <lifei.shirley@...edance.com>
Cc:     linux-kernel@...r.kernel.org, Jason Wang <jasowang@...hat.com>,
        Pawel Moll <pawel.moll@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Fam Zheng <zhengfeiran@...edance.com>
Subject: Re: [PATCH v1 0/2] virtio-mmio: support multiple interrupt vectors

On Fri, Jul 19, 2019 at 09:31:33PM +0800, Fei Li wrote:
> Hi,
> 
> This patch series implements multiple interrupt vectors support for
> virtio-mmio device. This is especially useful for multiqueue vhost-net
> device when using firecracker micro-vms as the guest.
> 
> Test result:
> With 8 vcpus & 8 net queues set, one vhost-net device with 8 irqs can
> receive 9 times more pps comparing with only one irq:
> - 564830.38 rxpck/s for 8 irqs on
> - 67665.06 rxpck/s for 1 irq on
> 
> Please help to review, thanks!
> 
> Have a nice day
> Fei


Interesting. The spec says though:

	4.2.3.4
	Notifications From The Device
	The memory mapped virtio device is using a single, dedicated interrupt signal, which is asserted when at
	least one of the bits described in the description of InterruptStatus is set. This is how the device sends a
	used buffer notification or a configuration change notification to the device.


So I'm guessing we need to change the host/guest interface?
If true pls cc virtio-dev.

Also, do we need to update dt bindings documentation?

> 
> Fam Zheng (1):
>   virtio-mmio: Process vrings more proactively
> 
> Fei Li (1):
>   virtio-mmio: support multiple interrupt vectors
> 
>  drivers/virtio/virtio_mmio.c | 238 +++++++++++++++++++++++++++++++++++--------
>  1 file changed, 196 insertions(+), 42 deletions(-)
> 
> -- 
> 2.11.0