Re: [PATCH 1/4] net: thunderx: Fix IOMMU translation faults

[Sunil Kovvuri]

>>
>> We are seeing a 0.75Mpps drop with IP forwarding rate due to that.
>> Hence I have restricted calling DMA interfaces to only when IOMMU is enabled.
>
> What's 0.07Mpps as a percentage of baseline? On a correctly configured
> coherent arm64 system, in the absence of an IOMMU, dma_map_*() is
> essentially just virt_to_phys() behind a function call or two, so I'd be
> interested to know where any non-trivial overhead might be coming from.

It's a 5% drop and yes device is configured as coherent.
And the drop is due to additional function calls.

Thanks,
Sunil.