1 .TH PBFIFO 8 "10 January 2002" "iproute2" "Linux"
3 pfifo \- Packet limited First In, First Out queue
5 bfifo \- Byte limited First In, First Out queue
8 .B tc qdisc ... add pfifo
13 .B tc qdisc ... add bfifo
19 The pfifo and bfifo qdiscs are unadorned First In, First Out queues. They are the
20 simplest queues possible and therefore have no overhead.
22 constrains the queue size as measured in packets.
24 does so as measured in bytes.
26 Like all non-default qdiscs, they maintain statistics. This might be a reason to prefer
27 pfifo or bfifo over the default.
30 A list of packets is maintained, when a packet is enqueued it gets inserted at the tail of
31 a list. When a packet needs to be sent out to the network, it is taken from the head of the list.
33 If the list is too long, no further packets are allowed on. This is called 'tail drop'.
38 Maximum queue size. Specified in bytes for bfifo, in packets for pfifo. For pfifo, defaults
39 to the interface txqueuelen, as specified with
43 The range for this parameter is [0, UINT32_MAX].
45 For bfifo, it defaults to the txqueuelen multiplied by the interface MTU.
46 The range for this parameter is [0, UINT32_MAX] bytes.
48 Note: The link layer header was considered when counting packets length.
53 contains the limit, either in packets or in bytes, and the number of bytes
54 and packets actually sent. An unsent and dropped packet only appears between braces
55 and is not counted as 'Sent'.
57 In this example, the queue length is 100 packets, 45894 bytes were sent over 681 packets.
58 No packets were dropped, and as the pfifo queue does not slow down packets, there were also no
62 # tc -s qdisc ls dev eth0
63 qdisc pfifo 8001: dev eth0 limit 100p
64 Sent 45894 bytes 681 pkts (dropped 0, overlimits 0)
67 If a backlog occurs, this is displayed as well.
72 Alexey N. Kuznetsov, <kuznet@ms2.inr.ac.ru>
74 This manpage maintained by bert hubert <ahu@ds9a.nl>