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SubjectRe: [PATCH v4 1/5] dma-mapping: Add dma_opt_mapping_size()
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On 28/06/2022 12:23, Robin Murphy wrote:
>> +
>> +    size_t
>> +    dma_opt_mapping_size(struct device *dev);
>> +
>> +Returns the maximum optimal size of a mapping for the device. Mapping
>> large
>> +buffers may take longer so device drivers are advised to limit total DMA
>> +streaming mappings length to the returned value.
>
> Nit: I'm not sure "advised" is necessarily the right thing to say in
> general - that's only really true for a caller who cares about
> throughput of churning through short-lived mappings more than anything
> else, and doesn't take a significant hit overall from splitting up
> larger requests. I do think it's good to clarify the exact context of
> "optimal" here, but I'd prefer to be objectively clear that it's for
> workloads where the up-front mapping overhead dominates.

Ok, sure, I can make that clear.

Thanks,
John

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