[PATCH iproute2] tc-cake: document 'ingress'

[PATCH iproute2] tc-cake: document 'ingress'

[Lương Việt Hoàng]

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>
---
 man/man8/tc-cake.8 | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/man/man8/tc-cake.8 b/man/man8/tc-cake.8
index ced9ac78..6d77d7d2 100644
--- 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
-- 
2.45.2

Re: [PATCH iproute2] tc-cake: document 'ingress'

[Stephen Hemminger]

On Sun, 11 Aug 2024 21:26:17 +0700
Lương Việt Hoàng <tcm4095@gmail.com> wrote:

>  .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

Hadn't looked at the man page for CAKE in detail before, but it appears
to be trying to pre-format lots of stuff rather than using man format (nroff)
like other man pages.

For example: indenting the start of the paragraph in nroff source is odd
and unnecessary.

Re: [PATCH iproute2] tc-cake: document 'ingress'

[a]

On Sun, Aug 11, 2024 at 11:35 PM Stephen Hemminger
<stephen@networkplumber.org> wrote:
> 
> Hadn't looked at the man page for CAKE in detail before, but it appears
> to be trying to pre-format lots of stuff rather than using man format (nroff)
> like other man pages.
> 
> For example: indenting the start of the paragraph in nroff source is odd
> and unnecessary.

I added a v2 that also reformats the man page to avoid pre-formatting.
Kindly check it here:
https://lore.kernel.org/netdev/20240812044234.3570-1-tcm4095@gmail.com/