The cross-channel feature allows to execute WQEs that involve
synchronization of I/O operations’ on different QPs.
This capability enables to program complex flows with a single
function call, hereby significantly reducing overhead associated
with I/O processing.
Cross-channel operations support is indicated by HCA capability
information.
The queue pairs can be configured to work as a “sync master queue”
or “sync slave queues”.
The added flags are:
1. Device capability flag IB_DEVICE_CROSS_CHANNEL for the
devices that can perform cross-channel operations.
2. CQ property flag IB_CQ_FLAGS_IGNORE_OVERRUN to disable CQ overrun
check. This check is useless in cross-channel scenario.
3. QP property flags to indicate if queues are slave or master:
* IB_QP_CREATE_MANAGED_SEND indicates that posted send work requests
will not be executed immediately and requires enabling.
* IB_QP_CREATE_MANAGED_RECV indicates that posted receive work
requests will not be executed immediately and requires enabling.
* IB_QP_CREATE_CROSS_CHANNEL declares the QP to work in cross-channel
mode. If IB_QP_CREATE_MANAGED_SEND and IB_QP_CREATE_MANAGED_RECV are
not provided, this QP will be sync master queue, else it will be sync
slave.
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
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