On Tue, Feb 02, 2021 at 09:13:09AM +0200, Leon Romanovsky wrote:

From: Yishai Hadas <yishaih@nvidia.com>

Cleanup the synchronize_srcu() from the ODP flow as it was found to be a
very heavy time consumer as part of dereg_mr.

For example de-registration of 10000 ODP MRs each with size of 2M
hugepage took 19.6 sec comparing de-registration of same number of non
ODP MRs that took 172 ms.

The new locking scheme uses the wait_event() mechanism which follows the
use count of the MR instead of using synchronize_srcu().

By that change, the time required for the above test took 95 ms which is
even better than the non ODP flow.

Once fully dropped the srcu usage, had to come with a lock to protect
the XA access.

As part of using the above mechanism we could also clean the
num_deferred_work stuff and follow the use count instead.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
Changelog:
v2:
 * Add checks of xa_erase() result as an outcome of memory error injection tests.
 * Found extra place where we can change open-coded logic to use mlx5r_store_odp_mkey().
v1: https://lore.kernel.org/linux-rdma/20210128064812.1921519-1-leon@kernel.org (local)
 * Deleted not-relevant comment implicit_get_child_mr(), I have no idea
   why wrong version of this patch was sent as v0.
 * Deleted two new break lines added by me to make code more uniformly
   in before "return ..." (sometimes it has new line, sometimes doesn't).
v0: https://lore.kernel.org/linux-rdma/20210127143051.1873866-1-leon@kernel.org (local)
---
 drivers/infiniband/hw/mlx5/devx.c            |  13 +-
 drivers/infiniband/hw/mlx5/main.c            |   5 -
 drivers/infiniband/hw/mlx5/mlx5_ib.h         |  31 ++-
 drivers/infiniband/hw/mlx5/mr.c              |  26 +--
 drivers/infiniband/hw/mlx5/odp.c             | 224 +++++++------------
 drivers/net/ethernet/mellanox/mlx5/core/mr.c |   1 +
 include/linux/mlx5/driver.h                  |   2 +
 7 files changed, 127 insertions(+), 175 deletions(-)

Applied to for-next, thanks

Jason