Re: [PATCH v4 4/7] s390/pci: Use dma-iommu layer

[Matthew Rosato]

On 1/19/23 6:03 AM, Niklas Schnelle wrote:
>>>>>>>>>>>>>>>>>  
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>  static char *pci_sw_names[] = {
>>>>>>>>>>>>>>>>> - "Allocated pages",
>>>>>>>>>>>>>>>>> +/* TODO "Allocated pages", */
>>>>>>>>>
>>>>>>>>> ? Forgot to finish this?
> 
> Definitely forgot to remove the TODO. I think my latest plan was to
> just remove this counter. With the DMA API conversion the
> dma_map_ops.alloc and dma_map_ops.free move to common code and I don't
> see how we could differentiate these from map/unmap on our side. I'm
> not sure how helpful this counter really is either. If you're
> interested in how many pages are mapped long term I think it makes more
> sense to look at the difference between mapped and unmapped pages. What
> do you think?
>>>>>>>>

Sounds reasonable to me, but I also note that without this series, when viewing statistics for a device, mapped - unmapped != allocated.  Maybe allocated pages was already broken, or is it taking into account something else that mapped - unmapped would not (maybe mapping the same page multiple times)?