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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