On Wed, May 27, 2020 at 11:34:51AM +0300, Yamin Friedman wrote: > This is the fourth re-incarnation of the CQ pool patches proposed > by Sagi and Christoph. I have started with the patches that Sagi last > submitted and built the CQ pool as a new API for acquiring shared CQs. > > The main change from Sagi's last proposal is that I have simplified the > method that ULP drivers interact with the CQ pool. Instead of calling > ib_alloc_cq they now call ib_cq_pool_get but use the CQ in the same manner > that they did before. This allows for a much easier transition to using > shared CQs by the ULP and makes it easier to deal with IB_POLL_DIRECT > contexts. Certain types of actions on CQs have been prevented on shared > CQs in order to prevent one user from harming another. > > Our ULPs often want to make smart decisions on completion vector > affinitization when using multiple completion queues spread on > multiple cpu cores. We can see examples for this in iser, srp, nvme-rdma. > > This patch set attempts to move this smartness to the rdma core by > introducing per-device CQ pools that by definition spread > across cpu cores. In addition, we completely make the completion > queue allocation transparent to the ULP by adding affinity hints > to create_qp which tells the rdma core to select (or allocate) > a completion queue that has the needed affinity for it. > > This API gives us a similar approach to whats used in the networking > stack where the device completion queues are hidden from the application. > With the affinitization hints, we also do not compromise performance > as the completion queue will be affinitized correctly. > > One thing that should be noticed is that now different ULPs using this > API may share completion queues (given that they use the same polling context). > However, even without this API they share interrupt vectors (and CPUs > that are assigned to them). Thus aggregating consumers on less completion > queues will result in better overall completion processing efficiency per > completion event (or interrupt). > > An advantage of this method of using the CQ pool is that changes in the ULP > driver are minimal (around 14 altered lines of code). > > The patch set converts nvme-rdma and nvmet-rdma to use the new API. > > Test results can be found in patch-0002. > > Comments and feedback are welcome. > > Changes since v3 > > *Refactored ib_poll_ctx enum > *Moved to correct use of unsigned types > *Removed use of spin_lock_irqsave > *Moved pool init and destroy function calls > *Corrected function documentation > > Changes since v2 > > *Minor code refactoring > > Changes since v1 > > *Simplified cq pool shutdown process > *Renamed cq pool functions to be like mr pool > *Simplified process for finding cqs in pool > *Removed unhelpful WARN prints > *Removed one liner functions > *Replaced cq_type with boolean shared > *Updated test results to more properly show effect of patch > *Minor bug fixes > > Yamin Friedman (4): > RDMA/core: Add protection for shared CQs used by ULPs > RDMA/core: Introduce shared CQ pool API > nvme-rdma: use new shared CQ mechanism > nvmet-rdma: use new shared CQ mechanism > > drivers/infiniband/core/core_priv.h | 3 + > drivers/infiniband/core/cq.c | 171 ++++++++++++++++++++++++++++++++++++ > drivers/infiniband/core/device.c | 2 + > drivers/infiniband/core/verbs.c | 9 ++ > drivers/nvme/host/rdma.c | 75 ++++++++++------ > drivers/nvme/target/rdma.c | 14 +-- > include/rdma/ib_verbs.h | 21 ++++- > 7 files changed, 261 insertions(+), 34 deletions(-) Applied to for-next, thanks Jason
