Adding upstream version 6.1.0.upstream/6.1.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 107 insertions, 0 deletions

diff --git a/man/man8/tc-fq.8 b/man/man8/tc-fq.8
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+.TH FQ 8 "10 Sept 2015" "iproute2" "Linux"
+.SH NAME
+FQ \- Fair Queue traffic policing
+.SH SYNOPSIS
+.B tc qdisc ... fq
+[
+.B limit
+PACKETS ] [
+.B flow_limit
+PACKETS ] [
+.B quantum
+BYTES ] [
+.B initial_quantum
+BYTES ] [
+.B maxrate
+RATE ] [
+.B buckets
+NUMBER ] [
+.B orphan_mask
+NUMBER ] [
+.B pacing
+|
+.B nopacing
+] [
+.B ce_threshold
+TIME ]
+
+.SH DESCRIPTION
+FQ (Fair Queue) is a classless packet scheduler meant to be mostly
+used for locally generated traffic.  It is designed to achieve per flow pacing.
+FQ does flow separation, and is able to respect pacing requirements set by TCP stack.
+All packets belonging to a socket are considered as a 'flow'.
+For non local packets (router workload), packet hash is used as fallback.
+
+An application can specify a maximum pacing rate using the
+.B SO_MAX_PACING_RATE
+setsockopt call.  This packet scheduler adds delay between packets to
+respect rate limitation set on each socket. Note that after linux-4.20, linux adopted EDT (Earliest Departure Time)
+and TCP directly sets the appropriate Departure Time for each skb.
+
+Dequeueing happens in a round-robin fashion.
+A special FIFO queue is reserved for high priority packets (
+.B TC_PRIO_CONTROL
+priority), such packets are always dequeued first.
+
+FQ is non-work-conserving.
+
+TCP pacing is good for flows having idle times, as the congestion
+window permits TCP stack to queue a possibly large number of packets.
+This removes the 'slow start after idle' choice, badly hitting
+large BDP flows and applications delivering chunks of data such as video streams.
+
+.SH PARAMETERS
+.SS limit
+Hard limit on the real queue size. When this limit is reached, new packets
+are dropped. If the value is lowered, packets are dropped so that the new limit is
+met. Default is 10000 packets.
+.SS flow_limit
+Hard limit on the maximum number of packets queued per flow.
+Default value is 100.
+.SS quantum
+The credit per dequeue RR round, i.e. the amount of bytes a flow is allowed to
+dequeue at once. A larger value means a longer time period before the next flow
+will be served.
+Default is 2 * interface MTU bytes.
+.SS initial_quantum
+The initial sending rate credit, i.e. the amount of bytes a new flow is allowed
+to dequeue initially.
+This is specifically meant to allow using IW10 without added delay.
+Default is 10 * interface MTU, i.e. 15140 for 'standard' ethernet.
+.SS maxrate
+Maximum sending rate of a flow.  Default is unlimited.
+Application specific setting via
+.B SO_MAX_PACING_RATE
+is ignored only if it is larger than this value.
+.SS buckets
+The size of the hash table used for flow lookups. Each bucket is assigned a
+red-black tree for efficient collision sorting.
+Default: 1024.
+.SS orphan_mask
+For packets not owned by a socket, fq is able to mask a part of skb->hash
+and reduce number of buckets associated with the traffic. This is a DDOS
+prevention mechanism, and the default is 1023 (meaning no more than 1024 flows
+are allocated for these packets)
+.SS [no]pacing
+Enable or disable flow pacing. Default is enabled.
+.SS ce_threshold
+sets a threshold above which all packets are marked with ECN Congestion
+Experienced. This is useful for DCTCP-style congestion control algorithms that
+require marking at very shallow queueing thresholds.
+
+.SH EXAMPLES
+#tc qdisc add dev eth0 root fq ce_threshold 4ms
+.br
+#tc -s -d qdisc show dev eth0
+.br
+qdisc fq 8001: dev eth0 root refcnt 2 limit 10000p flow_limit 100p buckets 1024 orphan_mask 1023 quantum 3028b initial_quantum 15140b low_rate_threshold 550Kbit refill_delay 40.0ms ce_threshold 4.0ms
+ Sent 72149092 bytes 48062 pkt (dropped 2176, overlimits 0 requeues 0)
+ backlog 1937920b 1280p requeues 0
+  flows 34 (inactive 17 throttled 0)
+  gc 0 highprio 0 throttled 0 ce_mark 47622 flows_plimit 2176
+.br
+.SH SEE ALSO
+.BR tc (8),
+.BR socket (7)
+.SH AUTHORS
+FQ was written by Eric Dumazet.