[RFC] User space to kernel space copy optimization

[okaya@codeaurora.org (Sinan Kaya)]

On 12/5/2015 3:10 AM, Vinod Koul wrote:
> On Mon, Nov 16, 2015 at 04:53:27PM -0500, Sinan Kaya 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.
>>
>> Of course, this will not be viable for all parameter sizes but I can see
>> this being useful. The goal is to save power in the cost of little
>> performance.
>>
>> Before I go and invent my own mechanism, I'd like to have ideas on what
>> an acceptable solution would look like. Especially, I'm looking for a
>> generic implementation that could plug into any DMA engine HW.
> 
> Do you have a proposal on how this generic solution should look like, broad
> contours of the design to start off with and we can start from that point
> 

No, not yet. AFAIK, some of these optimization ideas have been tried by
the Intel IO/AT in the past (kernel 2.6) and were rejected by the
upstream. I wanted to see if anybody had better ideas these days that is
upstream friendly.

-- 
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