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For many architectures the coherency is turned off and managed in software by the device driver, to achieve better performance.
by noselasd 9y ago
For many architectures the coherency is turned off and managed in software by the device driver, to achieve better performance.
- Unklejoe 9y agoAny examples of this in the Linux kernel? Not doubting you, I'm just curious. I would think this would be device driver specific rather than architecture specific. Most drivers I've seen just use the kernel's DMA API (dma_alloc_coherent), which is guaranteed to provide a buffer that doesn't require any explicit cache management. If the architecture is coherent, then it leaves caching turned on for those pages. If it's non-coherent, then it turns it off.