Re: [PATCH v4 5/6] iova: Add iova_len argument to init_iova_domain()

[John Garry]

On 02/08/2021 17:40, John Garry wrote:
> On 02/08/2021 17:16, Robin Murphy wrote:
> > On 2021-08-02 17:06, John Garry wrote:
> > > On 02/08/2021 16:06, Will Deacon wrote:
> > > > On Wed, Jul 14, 2021 at 06:36:42PM +0800, John Garry wrote:
> > > > > Add max opt argument to init_iova_domain(), and use it to set the 
> > > > > rcaches
> > > > > range.
> > > > >
> > > > > Also fix up all users to set this value (at 0, meaning use default).
> > > > Wrap that in init_iova_domain_defaults() to avoid the mysterious 0?
> > >
> > > Sure, I can do something like that. I actually did have separate 
> > > along those lines in v3 before I decided to change it.
> >
> > Y'know, at this point I'm now starting to seriously wonder whether 
> > moving the rcaches into iommu_dma_cookie wouldn't make a whole lot of 
> > things simpler... :/
>
> As I see, the rcache stuff isn't really specific to IOVA anyway, so it 
> seems sane.
>
> > Does that sound like crazy talk to you, or an idea worth entertaining?
>
> If you're going to start moving things, has anyone considered putting 
> rcache support in lib as a generic solution to "Magazines and Vmem: .." 
> paper?

Having said that, I still think that the rcache code has certain 
scalability issues, as discussed before. So making more generic and then 
discarding would be less than ideal.

Thanks,
john