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PBFIFO |
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!!!PBFIFO |
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NAME |
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SYNOPSIS |
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DESCRIPTION |
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ALGORITHM |
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PARAMETERS |
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OUTPUT |
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SEE ALSO |
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AUTHORS |
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---- |
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!!NAME |
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pfifo - Packet limited First In, First Out queue |
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bfifo - Byte limited First In, First Out queue |
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!!SYNOPSIS |
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__tc qdisc ... add pfifo [[ limit__ packets |
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__]__ |
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__tc qdisc ... add bfifo [[ limit__ bytes |
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__]__ |
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!!DESCRIPTION |
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The pfifo and bfifo qdiscs are unadorned First In, First Out |
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queues. They are the simplest queues possible and therefore |
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have no overhead. __pfifo__ constrains the queue size as |
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measured in packets. __bfifo__ does so as measured in |
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bytes. |
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Like all non-default qdiscs, they maintain statistics. This |
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might be a reason to prefer pfifo or bfifo over the |
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default. |
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!!ALGORITHM |
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A list of packets is maintained, when a packet is enqueued |
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it gets inserted at the tail of a list. When a packet needs |
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to be sent out to the network, it is taken from the head of |
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the list. |
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If the list is too long, no further packets are allowed on. |
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This is called 'tail drop'. |
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!!PARAMETERS |
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limit |
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Maximum queue size. Specified in bytes for bfifo, in packets |
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for pfifo. For pfifo, defaults to the interface txqueuelen, |
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as specified with ifconfig(8) or |
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ip(8). |
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For bfifo, it defaults to the txqueuelen multiplied by the |
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interface MTU. |
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!!OUTPUT |
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The output of __tc -s qdisc ls__ contains the limit, |
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either in packets or in bytes, and the number of bytes and |
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packets actually sent. An unsent and dropped packet only |
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appears between braces and is not counted as |
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'Sent'. |
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In this example, the queue length is 100 packets, 45894 |
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bytes were sent over 681 packets. No packets were dropped, |
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and as the pfifo queue does not slow down packets, there |
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were also no overlimits: |
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# tc -s qdisc ls dev eth0 |
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qdisc pfifo 8001: dev eth0 limit 100p |
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Sent 45894 bytes 681 pkts (dropped 0, overlimits 0) |
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If a backlog occurs, this is displayed as well. |
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!!SEE ALSO |
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tc(8) |
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!!AUTHORS |
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Alexey N. Kuznetsov, |
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This manpage maintained by bert hubert |
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---- |