On Tue, May 12, 2020 at 01:27:18PM -0700, Bart Van Assche wrote: > On 2020-05-12 13:13, Jason Gunthorpe wrote: > > On Tue, May 12, 2020 at 01:09:02PM -0700, Bart Van Assche wrote: > >> On 2020-05-12 10:16, Leon Romanovsky wrote: > >>> On Tue, May 12, 2020 at 07:08:59PM +0300, Israel Rukshin wrote: > >>>> FMR is not supported on most recent RDMA devices (that use fast memory > >>>> registration mechanism). Also, FMR was recently removed from NFS/RDMA > >>>> ULP. > >>>> > >>>> Signed-off-by: Israel Rukshin <israelr@xxxxxxxxxxxx> > >>>> Signed-off-by: Max Gurtovoy <maxg@xxxxxxxxxxxx> > >>>> drivers/infiniband/ulp/iser/iscsi_iser.h | 79 +---------- > >>>> drivers/infiniband/ulp/iser/iser_initiator.c | 19 ++- > >>>> drivers/infiniband/ulp/iser/iser_memory.c | 188 ++------------------------- > >>>> drivers/infiniband/ulp/iser/iser_verbs.c | 126 +++--------------- > >>>> 4 files changed, 40 insertions(+), 372 deletions(-) > >>> > >>> Can we do an extra step and remove FMR from srp too? > >> > >> Which HCA's will be affected by removing FMR support? Or in other words, > >> when did (Mellanox) HCA's start supporting fast memory registration? I'm > >> asking this because there is a tradition in the Linux kernel not to > >> remove support for old hardware unless it is pretty sure that nobody is > >> using that hardware anymore. > > > > We haven't entirely been following that in RDMA.. More like when > > people can't test any more it can go. > > > > For FMR the support was dropped in newer HW so AFAIK, nobody tests > > this and it just stands in the way of making FRWR work properly. > > > > Do the ULPs stop working or do they just run slower with some regular > > MR flow? > > I'm not sure. I do not have access to RDMA adapters that do not support > FRWR. > > A possible test is to check on websites for used products whether old > RDMA adapters are still available. Is the InfiniHost adapter one of the > adapters that supports FMR? It seems like that adapter is still easy to > find. I don't know - AFAIK nobody does any testing on those cards any more, and doesn't test the ULPs either. I know Leon has pushed to remove the mthca driver in the past. At one point there was a suggestion that drivers that do not support FRWR should be dropped, but I don't remember if mthca is the last one or not. There has been a big push to purge useless old stuff, look at the entire arch removals for instance. The large RDMA drivers fall under the same logic, IMHO. Jason
