On Thu, Jun 02, 2016 at 11:54:45AM +0530, Vikas Aggarwal wrote: > Hi list, > Will appreciate if someone can clear my doubts with "some theoretical > examples". I am trying to improve XOR/GF offload for a multi-core SoC > (currently it has single XOR/GF channel). > > 1) What is the purpose of device_prep_dma_interrupt callback ? > > 2) My driver currently polls for posting xor completions > (dma_cookie_complete) and does'nt use device_prep_dma_interrupt > callback at all. What gains/loss in terms of latency/cpu > idleness/WRITE throughput I can expect by implementing this callback > in my async_tx driver. > > 3) Purpose of DMA_ACK as I read - it is for higher layers to inform > dma driver that descriptors can now be freed. Can someone explain this > with an example as applicable with raid5/6 clients. > > 4) With example - why dma_run_dependencies(tx) needed after the > hardware engine post completion for a descriptor. > > 5) Purpose of tx->callback(cb_arg) - again with an example from a > raid5/6 offload perspective. > > I want to use offload engine efficiently with multithreaded raid5/6. > > I tried to dig through dma/drivers, crypto/async_xor.c, online > archives, linux/Documentation etc but could not get satisfactory > answers. Added two mail-lists as saw issues being discussed on both > ones. Did you read Documentation/crypto/async-tx-api.txt Also you should refer to code in crpto for dmaengine usage and other RAID examples. It would help if you post the code and ask people what you are trying to improve.. -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
