On Mon, Apr 15, 2013 at 4:39 AM, Simon Jeons wrote: > Hi Jerome, > On 02/10/2013 12:29 AM, Jerome Glisse wrote: > >> On Sat, Feb 9, 2013 at 1:05 AM, Michel Lespinasse >> wrote: >> >>> On Fri, Feb 8, 2013 at 3:18 AM, Shachar Raindel >>> wrote: >>> >>>> Hi, >>>> >>>> We would like to present a reference implementation for safely sharing >>>> memory pages from user space with the hardware, without pinning. >>>> >>>> We will be happy to hear the community feedback on our prototype >>>> implementation, and suggestions for future improvements. >>>> >>>> We would also like to discuss adding features to the core MM subsystem >>>> to >>>> assist hardware access to user memory without pinning. >>>> >>> This sounds kinda scary TBH; however I do understand the need for such >>> technology. >>> >>> I think one issue is that many MM developers are insufficiently aware >>> of such developments; having a technology presentation would probably >>> help there; but traditionally LSF/MM sessions are more interactive >>> between developers who are already quite familiar with the technology. >>> I think it would help if you could send in advance a detailed >>> presentation of the problem and the proposed solutions (and then what >>> they require of the MM layer) so people can be better prepared. >>> >>> And first I'd like to ask, aren't IOMMUs supposed to already largely >>> solve this problem ? (probably a dumb question, but that just tells >>> you how much you need to explain :) >>> >> For GPU the motivation is three fold. With the advance of GPU compute >> and also with newer graphic program we see a massive increase in GPU >> memory consumption. We easily can reach buffer that are bigger than >> 1gbytes. So the first motivation is to directly use the memory the >> user allocated through malloc in the GPU this avoid copying 1gbytes of >> data with the cpu to the gpu buffer. The second and mostly important >> > > The pinned memory you mentioned is the memory user allocated or the memory > of gpu buffer? > Memory user allocated, we don't want to pin this memory. Cheers, Jerome