On Tue, Jul 23, 2019 at 10:33 PM Leonardo Bras <leonardo@xxxxxxxxxxxxx> wrote: > > Hello everybody, > > I am not sure if this is the right place to be asking this. If is not, > I apologize for the inconvenience. Also, please tell me where is a > better way to as these questions. > > I am trying to create a basic C code to test vmsplice + SPLICE_F_GIFT > for moving memory pages between two processes without copying. > > I have followed the man pages and several recipes across the web, but I > could not reproduce it yet. > > Basically, I am doing: > Sending process: > - malloc + memcpy for generating pages to transfer > - vmsplice with SPLICE_F_GIFT sending over named pipe (in a loop) > Receiving process: > - Create mmaped file to receive the pages > - splice with SPLICE_F_MOVE receiving from named pipe (in a loop) As the splice(2) man page says SPLICE_F_MOVE is currently a no-op. > I have seen the SPLICE_F_MOVE being used on steal ops from the > 'pipebuffer', but I couldn't find a way to call it from splice. > > Questions: > It does what I think it does? (reassign memory pages from a process to > another) > If so, does page gifting still works? > If so, is there a basic recipe to test it's workings? What is the end goal? It is easy to transfer pages using shared memory (see shm_open(3) and related API), so why mess with splice? Thanks, Miklos
