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Subject: Re: [External Email] Re: [PATCH v1 0/2] virtio-mmio: support multiple interrupt vectors
On Mon, Jul 22, 2019 at 11:22:02AM +0800, æè wrote: > On Fri, Jul 19, 2019 at 11:14 PM Michael S. Tsirkin <mst@redhat.com> 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: > > > > 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. > > > 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? I'm not sure - so far irq was passed on the command line, right? The first step in implementing any spec change would be to update qemu code to virtio 1. Which is not a huge project but so far no one bothered. > > If true pls cc virtio-dev. > Sure. > > > > Also, do we need to update dt bindings documentation? > You mean the following doc? Sure. :) > https://github.com/torvalds/linux/blob/master/Documentation/devicetree/bindings/virtio/mmio.txt > > Thanks for the review! > > Have a nice day > Fei > > > > > > > > > > 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
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