linux.git/include/net/codel.h, branch v6.6.132

codel: fix kernel-doc notation warnings

2023-07-15T03:39:29+00:00

Use '@' before the struct member names in kernel-doc notation
to prevent kernel-doc warnings.

codel.h:158: warning: Function parameter or member 'ecn_mark' not described in 'codel_stats'
codel.h:158: warning: Function parameter or member 'ce_mark' not described in 'codel_stats'

Fixes: 76e3cc126bb2 ("codel: Controlled Delay AQM")
Signed-off-by: Randy Dunlap 
Cc: Jamal Hadi Salim 
Cc: Cong Wang 
Cc: Jiri Pirko 
Cc: Dave Taht 
Link: https://lore.kernel.org/r/20230714045127.18752-4-rdunlap@infradead.org
Signed-off-by: Jakub Kicinski

codel: remove unnecessary pkt_sched.h include

2021-12-22T23:03:51+00:00

Commit d068ca2ae2e6 ("codel: split into multiple files") moved all
Qdisc-related code to codel_qdisc.h, move the include of pkt_sched.h
as well.

This is similar to the previous commit, although we don't care as
much about incremental builds after pkt_sched.h was touched itself
it is included by net/sch_generic.h which is modified ~20 times
a year.

This decreases the incremental build size after touching pkt_sched.h
from 1592 to 617 objects.

Fix unmasked missing includes in WiFi drivers.

Acked-by: Kalle Valo 
Link: https://lore.kernel.org/r/20211221193941.3805147-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski

codel: remove unnecessary sock.h include

2021-12-22T23:03:47+00:00

Since sock.h is modified relatively often (60 times in the last
12 months) it seems worthwhile to decrease the incremental build
work.

CoDel's header includes net/inet_ecn.h which in turn includes net/sock.h.
codel.h is itself included by mac80211 which is included by much of
the WiFi stack and drivers. Removing the net/inet_ecn.h include from
CoDel breaks the dependecy between WiFi and sock.h.

Commit d068ca2ae2e6 ("codel: split into multiple files") moved all
the code which actually needs ECN helpers out to net/codel_impl.h,
the include can be moved there as well.

This decreases the incremental build size after touching sock.h
from 4999 objects to 4051 objects.

Fix unmasked missing includes in WiFi drivers.

Acked-by: Kalle Valo 
Link: https://lore.kernel.org/r/20211221193941.3805147-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski

fq_codel: generalise ce_threshold marking for subset of traffic

2021-10-20T22:24:36+00:00

Commit e72aeb9ee0e3 ("fq_codel: implement L4S style ce_threshold_ect1
marking") expanded the ce_threshold feature of FQ-CoDel so it can
be applied to a subset of the traffic, using the ECT(1) bit of the ECN
field as the classifier. However, hard-coding ECT(1) as the only
classifier for this feature seems limiting, so let's expand it to be more
general.

To this end, change the parameter from a ce_threshold_ect1 boolean, to a
one-byte selector/mask pair (ce_threshold_{selector,mask}) which is applied
to the whole diffserv/ECN field in the IP header. This makes it possible to
classify packets by any value in either the ECN field or the diffserv
field. In particular, setting a selector of INET_ECN_ECT_1 and a mask of
INET_ECN_MASK corresponds to the functionality before this patch, and a
mask of ~INET_ECN_MASK allows using the selector as a straight-forward
match against a diffserv code point:

 # apply ce_threshold to ECT(1) traffic
 tc qdisc replace dev eth0 root fq_codel ce_threshold 1ms ce_threshold_selector 0x1/0x3

 # apply ce_threshold to ECN-capable traffic marked as diffserv AF22
 tc qdisc replace dev eth0 root fq_codel ce_threshold 1ms ce_threshold_selector 0x50/0xfc

Regardless of the selector chosen, the normal rules for ECN-marking of
packets still apply, i.e., the flow must still declare itself ECN-capable
by setting one of the bits in the ECN field to get marked at all.

v2:
- Add tc usage examples to patch description

Signed-off-by: Toke Høiland-Jørgensen 
Reviewed-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20211019174709.69081-1-toke@redhat.com
Signed-off-by: Jakub Kicinski

fq_codel: implement L4S style ce_threshold_ect1 marking

2021-10-15T10:33:08+00:00

Add TCA_FQ_CODEL_CE_THRESHOLD_ECT1 boolean option to select Low Latency,
Low Loss, Scalable Throughput (L4S) style marking, along with ce_threshold.

If enabled, only packets with ECT(1) can be transformed to CE
if their sojourn time is above the ce_threshold.

Note that this new option does not change rules for codel law.
In particular, if TCA_FQ_CODEL_ECN is left enabled (this is
the default when fq_codel qdisc is created), ECT(0) packets can
still get CE if codel law (as governed by limit/target) decides so.

Section 4.3.b of current draft [1] states:

b.  A scheduler with per-flow queues such as FQ-CoDel or FQ-PIE can
    be used for L4S.  For instance within each queue of an FQ-CoDel
    system, as well as a CoDel AQM, there is typically also ECN
    marking at an immediate (unsmoothed) shallow threshold to support
    use in data centres (see Sec.5.2.7 of [RFC8290]).  This can be
    modified so that the shallow threshold is solely applied to
    ECT(1) packets.  Then if there is a flow of non-ECN or ECT(0)
    packets in the per-flow-queue, the Classic AQM (e.g.  CoDel) is
    applied; while if there is a flow of ECT(1) packets in the queue,
    the shallower (typically sub-millisecond) threshold is applied.

Tested:

tc qd replace dev eth1 root fq_codel ce_threshold_ect1 50usec

netperf ... -t TCP_STREAM -- K dctcp

tc -s -d qd sh dev eth1
qdisc fq_codel 8022: root refcnt 32 limit 10240p flows 1024 quantum 9212 target 5ms ce_threshold_ect1 49us interval 100ms memory_limit 32Mb ecn drop_batch 64
 Sent 14388596616 bytes 9543449 pkt (dropped 0, overlimits 0 requeues 152013)
 backlog 0b 0p requeues 152013
  maxpacket 68130 drop_overlimit 0 new_flow_count 95678 ecn_mark 0 ce_mark 7639
  new_flows_len 0 old_flows_len 0

[1] L4S current draft:
https://datatracker.ietf.org/doc/html/draft-ietf-tsvwg-l4s-arch

Signed-off-by: Eric Dumazet 
Cc: Neal Cardwell 
Cc: Ingemar Johansson S 
Cc: Tom Henderson 
Cc: Bob Briscoe 
Signed-off-by: David S. Miller

codel: split into multiple files

2016-04-25T20:44:27+00:00

It was impossible to include codel.h for the
purpose of having access to codel_params or
codel_vars structure definitions and using them
for embedding in other more complex structures.

This splits allows codel.h itself to be treated
like any other header file while codel_qdisc.h and
codel_impl.h contain function definitions with
logic that was previously in codel.h.

This copies over copyrights and doesn't involve
code changes other than adding a few additional
include directives to net/sched/sch*codel.c.

Signed-off-by: Michal Kazior 
Signed-off-by: David S. Miller

codel: generalize the implementation

2016-04-25T20:44:27+00:00

This strips out qdisc specific bits from the code
and makes it slightly more reusable. Codel will be
used by wireless/mac80211 in the future.

Signed-off-by: Michal Kazior 
Signed-off-by: David S. Miller

net_sched: update hierarchical backlog too

2016-02-29T22:02:33+00:00

When the bottom qdisc decides to, for example, drop some packet,
it calls qdisc_tree_decrease_qlen() to update the queue length
for all its ancestors, we need to update the backlog too to
keep the stats on root qdisc accurate.

Cc: Jamal Hadi Salim 
Acked-by: Jamal Hadi Salim 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2015-05-13T18:31:43+00:00

Four minor merge conflicts:

1) qca_spi.c renamed the local variable used for the SPI device
   from spi_device to spi, meanwhile the spi_set_drvdata() call
   got moved further up in the probe function.

2) Two changes were both adding new members to codel params
   structure, and thus we had overlapping changes to the
   initializer function.

3) 'net' was making a fix to sk_release_kernel() which is
   completely removed in 'net-next'.

4) In net_namespace.c, the rtnl_net_fill() call for GET operations
   had the command value fixed, meanwhile 'net-next' adjusted the
   argument signature a bit.

This also matches example merge resolutions posted by Stephen
Rothwell over the past two days.

Signed-off-by: David S. Miller

codel: add ce_threshold attribute

2015-05-10T23:50:20+00:00

For DCTCP or similar ECN based deployments on fabrics with shallow
buffers, hosts are responsible for a good part of the buffering.

This patch adds an optional ce_threshold to codel & fq_codel qdiscs,
so that DCTCP can have feedback from queuing in the host.

A DCTCP enabled egress port simply have a queue occupancy threshold
above which ECT packets get CE mark.

In codel language this translates to a sojourn time, so that one doesn't
have to worry about bytes or bandwidth but delays.

This makes the host an active participant in the health of the whole
network.

This also helps experimenting DCTCP in a setup without DCTCP compliant
fabric.

On following example, ce_threshold is set to 1ms, and we can see from
'ldelay xxx us' that TCP is not trying to go around the 5ms codel
target.

Queue has more capacity to absorb inelastic bursts (say from UDP
traffic), as queues are maintained to an optimal level.

lpaa23:~# ./tc -s -d qd sh dev eth1
qdisc mq 1: dev eth1 root
 Sent 87910654696 bytes 58065331 pkt (dropped 0, overlimits 0 requeues 42961)
 backlog 3108242b 364p requeues 42961
qdisc codel 8063: dev eth1 parent 1:1 limit 1000p target 5.0ms ce_threshold 1.0ms interval 100.0ms
 Sent 7363778701 bytes 4863809 pkt (dropped 0, overlimits 0 requeues 5503)
 rate 2348Mbit 193919pps backlog 255866b 46p requeues 5503
  count 0 lastcount 0 ldelay 1.0ms drop_next 0us
  maxpacket 68130 ecn_mark 0 drop_overlimit 0 ce_mark 72384
qdisc codel 8064: dev eth1 parent 1:2 limit 1000p target 5.0ms ce_threshold 1.0ms interval 100.0ms
 Sent 7636486190 bytes 5043942 pkt (dropped 0, overlimits 0 requeues 5186)
 rate 2319Mbit 191538pps backlog 207418b 64p requeues 5186
  count 0 lastcount 0 ldelay 694us drop_next 0us
  maxpacket 68130 ecn_mark 0 drop_overlimit 0 ce_mark 69873
qdisc codel 8065: dev eth1 parent 1:3 limit 1000p target 5.0ms ce_threshold 1.0ms interval 100.0ms
 Sent 11569360142 bytes 7641602 pkt (dropped 0, overlimits 0 requeues 5554)
 rate 3041Mbit 251096pps backlog 210446b 59p requeues 5554
  count 0 lastcount 0 ldelay 889us drop_next 0us
  maxpacket 68130 ecn_mark 0 drop_overlimit 0 ce_mark 37780
...

Signed-off-by: Eric Dumazet 
Cc: Florian Westphal 
Cc: Daniel Borkmann 
Cc: Glenn Judd 
Cc: Nandita Dukkipati 
Cc: Neal Cardwell 
Cc: Yuchung Cheng 
Acked-by: Neal Cardwell 
Signed-off-by: David S. Miller