Hi folks, Just wanted your thoughts/suggestions on how we can avoid overhead in the EDMA dmaengine driver. I am seeing a lots of performance drop specially for small transfers with EDMA versus before raw EDMA was moved to DMAEngine framework (atleast 25%).
One of the things I am thinking about is the repeated (spin) locking/unlocking of the virt_dma_chan->lock or vc->lock. In many cases, there's only 1 user or thread requiring to do a DMA, so I feel the locking is unnecessary and potential overhead. If there's a sane way to detect this an avoid locking altogether, that would be great. Also with respect to virt_dma (which is used by edma to manage all the descriptors and lists) there are too many lists: submitted, issued, completed etc and the descriptor moves from one to the other. I am thinking if there is a way we can avoid using so many lists and just have 2 lists and move the desc from one list to the other, That could avoid using the intermediate list altogether and classify dma requests as "done" or "not done". Since this involves discussing concurrency primitives, copying linux-rt-users as well. Thanks, -Joel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
