tc-cake: document 'ingress'

Linux kernel commit 7298de9cd7255a783ba ("sch_cake: Add ingress mode") added
an ingress mode for CAKE, which can be enabled with the 'ingress' parameter.
Document the changes in CAKE's behavior when ingress mode is enabled.

Signed-off-by: Lương Việt Hoàng <tcm4095@gmail.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@kernel.org>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

diff --git a/man/man8/tc-cake.8 b/man/man8/tc-cake.8
index ced9ac78ccca49c9a11d2ec058b54791dce74ba9..6d77d7d2f9784a49727247cc070ad7b5e67ec7a1 100644 (file)
--- a/man/man8/tc-cake.8
+++ b/man/man8/tc-cake.8
@@ -541,6 +541,21 @@ This can be used to set policies in a firewall script that will override CAKE's
 built-in tin selection.
 
 .SH OTHER PARAMETERS
+.B ingress
+.br
+       Indicates that CAKE is running in ingress mode (i.e. running on the downlink
+of a connection). This changes the shaper to also count dropped packets as data
+transferred, as these will have already traversed the link before CAKE can
+choose what to do with them.
+
+       In addition, the AQM will be tuned to always keep at least two packets
+queued per flow. The reason for this is that retransmits are more expensive in
+ingress mode, since dropped packets have to traverse the link again; thus,
+keeping a minimum number of packets queued will improve throughput in cases
+where the number of active flows are so large that they saturate the link even
+at their minimum window size.
+
+.PP
 .B memlimit
 LIMIT
 .br