Messages in this thread |  | | Date | Sun, 5 Jan 2020 06:25:59 -0500 | From | "Michael S. Tsirkin" <> | Subject | Re: [virtio-dev] Re: [PATCH v1 2/2] virtio-mmio: add features for virtio-mmio specification version 3 |
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On Fri, Jan 03, 2020 at 05:12:38PM +0800, Jason Wang wrote: > > On 2020/1/3 下午2:14, Liu, Jiang wrote: > > > Ok, I get you now. > > > > > > But still, having fixed number of MSIs is less flexible. E.g: > > > > > > - for x86, processor can only deal with about 250 interrupt vectors. > > > - driver may choose to share MSI vectors [1] (which is not merged but we will for sure need it) > > Thanks for the info:) > > X86 systems roughly have NCPU * 200 vectors available for device interrupts. > > The proposed patch tries to map multiple event sources to an interrupt vector, to avoid running out of x86 CPU vectors. > > Many virtio mmio devices may have several or tens of event sources, and it’s rare to have hundreds of event sources. > > So could we treat the dynamic mapping between event sources and interrupt vectors as an advanced optional feature? > > > > Maybe, but I still prefer to implement it if it is not too complex. Let's > see Michael's opinion on this. > > Thanks
I think a way for the device to limit # of vectors in use by driver is useful. But sharing of vectors doesn't really need any special registers, just program the same vector for multiple Qs/interrupts.
-- MST
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