Provided by: freebsd-manpages_12.2-1_all 
NAME
iflib — Network Interface Driver Framework
SYNOPSIS
device pci
device iflib
DESCRIPTION
iflib is a framework for network interface drivers for FreeBSD. It is designed to remove a
large amount of the boilerplate that is often needed for modern network interface devices,
allowing driver authors to focus on the specific code needed for their hardware. This
allows for a shared set of sysctl(8) names, rather than each driver naming them
individually.
SYSCTL VARIABLES
These variables must be set before loading the driver, either via loader.conf(5) or through
the use of kenv(1). They are all prefixed by dev.X.Y.iflib. where X is the driver name, and
Y is the instance number.
override_nrxds
Override the number of RX descriptors for each queue. The value is a comma
separated list of positive integers. Some drivers only use a single value, but
others may use more. These numbers must be powers of two, and zero means to use the
default. Individual drivers may have additional restrictions on allowable values.
Defaults to all zeros.
override_ntxds
Override the number of TX descriptors for each queue. The value is a comma
separated list of positive integers. Some drivers only use a single value, but
others may use more. These numbers must be powers of two, and zero means to use the
default. Individual drivers may have additional restrictions on allowable values.
Defaults to all zeros.
override_qs_enable
When set, allows the number of transmit and receive queues to be different. If not
set, the lower of the number of TX or RX queues will be used for both.
override_nrxqs
Set the number of RX queues. If zero, the number of RX queues is derived from the
number of cores on the socket connected to the controller. Defaults to 0.
override_ntxqs
Set the number of TX queues. If zero, the number of TX queues is derived from the
number of cores on the socket connected to the controller.
disable_msix
Disables MSI-X interrupts for the device.
core_offset
Specifies a starting core offset to assign queues to. If the value is unspecified
or 65535, cores are assigned sequentially across controllers.
separate_txrx
Requests that RX and TX queues not be paired on the same core. If this is zero or
not set, an RX and TX queue pair will be assigned to each core. When set to a non-
zero value, TX queues are assigned to cores following the last RX queue.
These sysctl(8) variables can be changed at any time:
tx_abdicate
Controls how the transmit ring is serviced. If set to zero, when a frame is
submitted to the transmission ring, the same task that is submitting it will service
the ring unless there's already a task servicing the TX ring. This ensures that
whenever there is a pending transmission, the transmit ring is being serviced. This
results in higher transmit throughput. If set to a non-zero value, task returns
immediately and the transmit ring is serviced by a different task. This returns
control to the caller faster and under high receive load, may result in fewer
dropped RX frames.
rx_budget
Sets the maximum number of frames to be received at a time. Zero (the default)
indicates the default (currently 16) should be used.
There are also some global sysctls which can change behaviour for all drivers, and may be
changed at any time.
net.iflib.min_tx_latency
If this is set to a non-zero value, iflib will avoid any attempt to combine multiple
transmits, and notify the hardware as quickly as possible of new descriptors. This
will lower the maximum throughput, but will also lower transmit latency.
net.iflib.no_tx_batch
Some NICs allow processing completed transmit descriptors in batches. Doing so
usually increases the transmit throughput by reducing the number of transmit
interrupts. Setting this to a non-zero value will disable the use of this feature.
These sysctl(8) variables are read-only:
driver_version
A string indicating the internal version of the driver.
There are a number of queue state sysctl(8) variables as well:
txqZ The following are repeated for each transmit queue, where Z is the transmit queue
instance number:
r_abdications
Number of consumer abdications in the MP ring for this queue. An abdication
occurs on every ring submission when tx_abdicate is true.
r_restarts
Number of consumer restarts in the MP ring for this queue. A restart occurs
when an attempt to drain a non-empty ring fails, and the ring is already in
the STALLED state.
r_stalls
Number of consumer stalls in the MP ring for this queue. A stall occurs
when an attempt to drain a non-empty ring fails.
r_starts
Number of normal consumer starts in the MP ring for this queue. A start
occurs when the MP ring transitions from IDLE to BUSY.
r_drops
Number of drops in the MP ring for this queue. A drop occurs when there is
an attempt to add an entry to an MP ring with no available space.
r_enqueues
Number of entries which have been enqueued to the MP ring for this queue.
ring_state
MP (soft) ring state. This privides a snapshot of the current MP ring
state, including the producer head and tail indexes, the consumer index, and
the state. The state is one of "IDLE", "BUSY", "STALLED", or "ABDICATED".
txq_cleaned
The number of transmit descriptors which have been reclaimed. Total
cleaned.
txq_processed
The number of transmit descriptors which have been processed, but may not
yet have been reclaimed.
txq_in_use
Descriptors which have been added to the transmit queue, but have not yet
been cleaned. This value will include both untransmitted descriptors as
well as descriptors which have been processed.
txq_cidx_processed
The transmit queue consumer index of the next descriptor to process.
txq_cidx
The transmit queue consumer index of the oldest descriptor to reclaim.
txq_pidx
The transmit queue producer index where the next descriptor to transmit will
be inserted.
no_tx_dma_setup
Number of times DMA mapping a transmit mbuf failed for reasons other than
EFBIG.
txd_encap_efbig
Number of times DMA mapping a transmit mbuf failed due to requiring too many
segments.
tx_map_failed
Number of times DMA mapping a transmit mbuf failed for any reason (sum of
no_tx_dma_setup and txd_encap_efbig)
no_desc_avail
Number of times a descriptor couldn't be added to the transmit ring because
the transmit ring was full.
mbuf_defrag_failed
Number of times both m_collapse(9) and m_defrag(9) failed after an EFBIG
error result from DMA mapping a transmit mbuf.
m_pullups
Number of times m_pullup(9) was called attempting to parse a header.
mbuf_defrag
Number of times m_defrag(9) was called.
rxqZ The following are repeated for each receive queue, where Z is the receive queue
instance number:
rxq_fl0.credits
Credits currently available in the receive ring.
rxq_fl0.cidx
Current receive ring consumer index.
rxq_fl0.pidx
Current receive ring producer index.
Additional OIDs useful for driver and iflib development are exposed when the INVARIANTS
and/or WITNESS options are enabled in the kernel.
SEE ALSO
iflib(9)
HISTORY
This framework was introduced in FreeBSD 11.0.