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

[Jason Wang]

On 2020/12/9 下午6:58, Stefano Garzarella wrote:
> 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?


Per-device should be ok.

Thanks


> Thanks,
> Stefano