Re: [PATCH v3 05/19] vdpa_sim: remove the limit of IOTLB entries

[Stefano Garzarella]

On Mon, Dec 07, 2020 at 12:00:07PM +0800, Jason Wang wrote:
> On 2020/12/4 上午1:04, Stefano Garzarella wrote:
> > The simulated devices can support multiple queues, so this limit
> > should be defined according to the number of queues supported by
> > the device.
> >
> > Since we are in a simulator, let's simply remove that limit.
> >
> > Suggested-by: Jason Wang <jasowang@xxxxxxxxxx>
> > Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
> > Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
>
>
> Rethink about this, since simulator can be used by VM, so the 
> allocation is actually guest trigger-able when vIOMMU is enabled.
>
> This means we need a limit somehow, (e.g I remember swiotlb is about 
> 64MB by default). Or having a module parameter for this.
>
> Btw, have you met any issue when using 2048, I guess it can happen 
> when we run several processes in parallel?

No, I didn't try with the limit.
This came from the reviews to Max's patches.

Anyway I can add a module parameter to control that limit, do you think 
is better to set a limit per queue (the parameter per number of queues), 
or just a value for the entire device?

Thanks,
Stefano