I see that the schedule is not full yet for the mm track and i would really like to be able to have a discussion on this topic Schedule: https://docs.google.com/spreadsheets/d/1Z1pDL-XeUT1ZwMWrBL8T8q3vtSqZpLPgF3Bzu_jejfk/edit#gid=0 On Fri, Jan 18, 2019 at 12:45:13PM -0500, Jerome Glisse wrote: > Hi, i would like to discuss about NUMA API and its short comings when > it comes to memory hierarchy (from fast HBM, to slower persistent > memory through regular memory) and also device memory (which can have > its own hierarchy). > > I have proposed a patch to add a new memory topology model to the > kernel for application to be able to get that informations, it > also included a set of new API to bind/migrate process range [1]. > Note that this model also support device memory. > > So far device memory support is achieve through device specific ioctl > and this forbid some scenario like device memory interleaving accross > multiple devices for a range. It also make the whole userspace more > complex as program have to mix and match multiple device specific API > on top of NUMA API. > > While memory hierarchy can be more or less expose through the existing > NUMA API by creating node for non-regular memory [2], i do not see this > as a satisfying solution. Moreover such scheme does not work for device > memory that might not even be accessible by CPUs. > > > Hence i would like to discuss few points: > - What proof people wants to see this as problem we need to solve ? > - How to build concensus to move forward on this ? > - What kind of syscall API people would like to see ? > > People to discuss this topic: > Dan Williams <dan.j.williams@xxxxxxxxx> > Dave Hansen <dave.hansen@xxxxxxxxx> > Felix Kuehling <Felix.Kuehling@xxxxxxx> > John Hubbard <jhubbard@xxxxxxxxxx> > Jonathan Cameron <jonathan.cameron@xxxxxxxxxx> > Keith Busch <keith.busch@xxxxxxxxx> > Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> > Michal Hocko <mhocko@xxxxxxxxxx> > Paul Blinzer <Paul.Blinzer@xxxxxxx> > > Probably others, sorry if i miss anyone from previous discussions. > > Cheers, > Jérôme > > [1] https://lkml.org/lkml/2018/12/3/1072 > [2] https://lkml.org/lkml/2018/12/10/1112 >
