lkml.org 
[lkml]   [2020]   [Jan]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [virtio-dev] Re: [PATCH v1 2/2] virtio-mmio: add features for virtio-mmio specification version 3
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

\
 
 \ /
  Last update: 2020-01-05 12:26    [W:0.130 / U:14.444 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site