* [PATCH rdma-next v2 0/4] Improve ODP by using HMM API
@ 2020-09-22 8:21 Leon Romanovsky
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From: Leon Romanovsky @ 2020-09-22 8:21 UTC (permalink / raw)
To: Doug Ledford, Jason Gunthorpe
Cc: Leon Romanovsky, linux-kernel, linux-rdma, Yishai Hadas,
Christoph Hellwig
From: Leon Romanovsky <leonro@nvidia.com>
Changelog:
v2:
* Patch #1 – Drop redundant mask.
* Patch #4 – Use address and length directly from umem_odp.
v1: https://lore.kernel.org/lkml/20200917112152.1075974-1-leon@kernel.org
* Cleaned code.
* Support a potential valid dma_address of NULL by flags detection,
note was added to clarify things as was asked.
* Fix 80 character lines in few places.
v0: https://lore.kernel.org/lkml/20200914113949.346562-1-leon@kernel.org
Based on:
https://lore.kernel.org/lkml/20200914112653.345244-1-leon@kernel.org/
---------------------------------------------------------------------------------------
From Yishai:
This series improves ODP performance by moving to use the HMM API as of below.
The get_user_pages_remote() functionality was replaced by HMM:
- No need anymore to allocate and free memory to hold its output per call.
- No need anymore to use the put_page() to unpin the pages.
- The logic to detect contiguous pages is done based on the returned order
from HMM, no need to run per page, and evaluate.
Moving to use the HMM enables to reduce page faults in the system by using the
snapshot mode. This mode allows existing pages in the CPU to become presented
to the device without faulting.
This non-faulting mode may be used explicitly by an application with some new
option of advice MR (i.e. PREFETCH_NO_FAULT) and is used upon ODP MR
registration internally as part of initiating the device page table.
To achieve the above, internal changes in the ODP data structures were done
and some flows were cleaned-up/adapted accordingly.
Thanks
Yishai Hadas (4):
IB/core: Improve ODP to use hmm_range_fault()
IB/core: Enable ODP sync without faulting
RDMA/mlx5: Extend advice MR to support non faulting mode
RDMA/mlx5: Sync device with CPU pages upon ODP MR registration
drivers/infiniband/Kconfig | 1 +
drivers/infiniband/core/umem_odp.c | 285 ++++++++++--------------
drivers/infiniband/hw/mlx5/mlx5_ib.h | 5 +
drivers/infiniband/hw/mlx5/mr.c | 14 +-
drivers/infiniband/hw/mlx5/odp.c | 48 ++--
include/rdma/ib_umem_odp.h | 21 +-
include/uapi/rdma/ib_user_ioctl_verbs.h | 1 +
7 files changed, 173 insertions(+), 202 deletions(-)
--
2.26.2
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