трехдиапазонная очередь «первым пришел - первым вышел» (three-band first in, first out queue)
Имя (Name)
pfifo_fast - three-band first in, first out queue
Описание (Description)
pfifo_fast is the default qdisc of each interface.
Whenever an interface is created, the pfifo_fast qdisc is
automatically used as a queue. If another qdisc is attached, it
preempts the default pfifo_fast, which automatically returns to
function when an existing qdisc is detached.
In this sense this qdisc is magic, and unlike other qdiscs.
Алгоритм (Algorithm)
The algorithm is very similar to that of the classful tc-prio(8)
qdisc. pfifo_fast is like three tc-pfifo(8) queues side by side,
where packets can be enqueued in any of the three bands based on
their Type of Service bits or assigned priority.
Not all three bands are dequeued simultaneously - as long as
lower bands have traffic, higher bands are never dequeued. This
can be used to prioritize interactive traffic or penalize 'lowest
cost' traffic.
Each band can be txqueuelen packets long, as configured with
ifconfig(8) or ip(8). Additional packets coming in are not
enqueued but are instead dropped.
See tc-prio(8) for complete details on how TOS bits are
translated into bands.
Параметры (Parameters)
txqueuelen
The length of the three bands depends on the interface
txqueuelen, as specified with ifconfig(8) or ip(8).
Ошибки (баги) (Bugs)
Does not maintain statistics and does not show up in tc qdisc ls.
This is because it is the automatic default in the absence of a
configured qdisc.
Смотри также (See also)
tc(8)
