On 11/16/2015 5:57 PM, Jiang, Dave wrote: >> One of the things I'm interested in is to use a memcpy capable DMA >> > engine HW to optimize user space and kernel space parameter copying. > Have you looked at why NET_DMA was deprecated and using DMA engine to > do kernel->user copy could be a problem? > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/ > ?id=77873803363c > As far as I know, the problem was the TCP/IP stack trying to work on a buffer that was given to the DMA engine for moving. It was causing stale data problems. The goal was to let DMA engine move the data while TCP/IP stack was working on something else. Then, synchronize on a known point. Of course, when above violation happens; things break. Are you expecting a similar problem on user space to kernel space interaction? I think the ownership buffers are pretty much defined, isn't it? -- Sinan Kaya Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project -- 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
