On Mon, 2015-11-16 at 23:19 +0000, Sinan Kaya wrote: > 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/com > > mit/ > > ?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? No. I thought you were investigating both ways so thought you might need to be aware. > > > -- > 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��.n��������+%������w��{.n��������)�)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
