Re: [External Email] Re: [PATCH v1 0/2] virtio-mmio: support multiple interrupt vectors
Date: Sun Jul 21 2019 - 23:22:16 EST
On Fri, Jul 19, 2019 at 11:14 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
> 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:
> 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.
Yes, the spec needs to be updated if we want to use mult-irqs.
> So I'm guessing we need to change the host/guest interface?
Just to confirm, does the "the host/guest interface" you mentioned mean how to
pass the irq information from the user space tool to guest kernel?
In this patch, we do this by passing the [irq_start, irq_end]
interface via setting guest
kernel command line, that is done in vm_cmdline_set().
Also there is another way to do this: add two new registers describing irq info
(irq_start & irq_end OR irq_start & irq_numbers) to the virtio config space.
Which one do you prefer?
> If true pls cc virtio-dev.
> Also, do we need to update dt bindings documentation?
You mean the following doc? Sure. :)
Thanks for the review!
Have a nice day
> > 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