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In a real dma mapping user case, after dma_map is done, data will be transmit. Thus, in multi-threaded user scenario, IOMMU contention should not be that severe. For example, if users enable multiple threads to send network packets through 1G/10G/100Gbps NIC, usually the steps will be: map -> transmission -> unmap. Transmission delay reduces the contention of IOMMU. Here a delay is added to simulate the transmission between map and unmap so that the tested result could be more accurate for TX and simple RX. A typical TX transmission for NIC would be like: map -> TX -> unmap since the socket buffers come from OS. Simple RX model eg. disk driver, is also map -> RX -> unmap, but real RX model in a NIC could be more complicated considering packets can come spontaneously and many drivers are using pre-mapped buffers pool. This is in the TBD list. Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Signed-off-by: Christoph Hellwig <hch@lst.de> |
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| dma_map_benchmark.c | ||
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