Messages in this thread | | | Subject | Re: [RFC] User space to kernel space copy optimization | From | Sinan Kaya <> | Date | Mon, 16 Nov 2015 18:19:14 -0500 |
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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
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