On 5/13/2020 3:18 AM, Leon Romanovsky wrote:
On Tue, May 12, 2020 at 05:53:34PM -0700, Sagi Grimberg 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.
I think we should remove this support, if there is a user of this
somewhere he can safely use iscsi. Let alone that iser uses the fmr
pools which leaves rkeys exposed for caching purposes. So I'd much
rather remove it than trying to fix it.
Agree, given the fact that no one is even going to try to fix.
We don't see new contributors in this community who are not affiliated
with RDMA companies and they are not testing and have no plans to test FMR.
I feel that we can't even say if FMR and old cards work :).
qib still works.
-Denny
