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[RFC,v2,0/7] introduce new barrier class and use it for mlx5 PMD

Message ID 20200410164127.54229-1-gavin.hu@arm.com (mailing list archive)
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Gavin Hu April 10, 2020, 4:41 p.m. UTC 
To order writes to various memory types, 'sfence' is required for x86,
and 'dmb oshst' is required for aarch64. 

But within DPDK, there is no abstracted barriers covers this
combination: sfence(x86)/dmb(aarch64).

So introduce a new barrier class - rte_dma_*mb for this combination, 

Doorbell rings are typical use cases of this new barrier class, which
requires something ready in the memory before letting HW aware.

As a note, rte_io_wmb and rte_cio_wmb are compiler barriers for x86, while
rte_wmb is 'dsb' for aarch64.

In the joint preliminary testing between Arm and Ampere, 8%~13%
performance boost was measured.

As there is no functionality changes, it will not impact x86. 

Gavin Hu (6):
  eal: introduce new class of barriers for DMA use cases
  net/mlx5: dmb for immediate doorbell ring on aarch64
  net/mlx5: relax barrier to order UAR writes on aarch64
  net/mlx5: relax barrier for aarch64
  net/mlx5: add descriptive comment for a barrier
  doc: clarify one configuration in mlx5 guide

Phil Yang (1):
  net/mlx5: relax ordering for multi-packet RQ buffer refcnt

 doc/guides/nics/mlx5.rst                    |  6 ++--
 drivers/net/mlx5/mlx5_rxq.c                 |  2 +-
 drivers/net/mlx5/mlx5_rxtx.c                | 16 ++++++-----
 drivers/net/mlx5/mlx5_rxtx.h                | 14 ++++++----
 lib/librte_eal/arm/include/rte_atomic_32.h  |  6 ++++
 lib/librte_eal/arm/include/rte_atomic_64.h  |  6 ++++
 lib/librte_eal/include/generic/rte_atomic.h | 31 +++++++++++++++++++++
 lib/librte_eal/ppc/include/rte_atomic.h     |  6 ++++
 lib/librte_eal/x86/include/rte_atomic.h     |  6 ++++
 9 files changed, 78 insertions(+), 15 deletions(-)