- Name
-
ctpio - Default
-
1 - Minimum
-
0 - Maximum
-
2 - Scope
- per-stack
Controls whether the CTPIO low-latency transmit mechanism is enabled:
-
0– no (use DMA and/or PIO) -
1– enable CTPIO if available (default) -
2– enable CTPIO and fail stack creation if not available.
Mode 1 will fall back to DMA or PIO if CTPIO is not currently available. Mode 2 will fail to create the stack if the hardware supports CTPIO but CTPIO is not currently available. On hardware that does not support CTPIO there is no difference between mode 1 and mode 2.
In all cases, CTPIO is only be used for packets if length ≤ EF_CTPIO_MAX_FRAME_LEN and when the VI's transmit queue is empty. If these conditions are not met DMA or PIO is used, even in mode 2.
Note: CTPIO is currently only available on x86_64 systems.
Note: Mode
2 will not prevent a stack from operating without CTPIO in the event that CTPIO allocation is originally successful but then fails after an adapter is rebooted or hotplugged while that stack exists.