diff mbox series

[RFC,net-next,1/2] ipv6: ioam: Support for Queue depth data field

Message ID 20211206211758.19057-2-justin.iurman@uliege.be (mailing list archive)
State RFC
Delegated to: Netdev Maintainers
Headers show
Series IOAM queue depth and buffer occupancy | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit fail Errors and warnings before: 0 this patch: 1
netdev/cc_maintainers success CCed 5 of 5 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn fail Errors and warnings before: 0 this patch: 1
netdev/checkpatch warning WARNING: line length of 81 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Justin Iurman Dec. 6, 2021, 9:17 p.m. UTC
This patch is an attempt to support the queue depth in IOAM trace data
fields. Any feedback is appreciated, or any other idea if this one is
not correct.

The draft [1] says the following:

   The "queue depth" field is a 4-octet unsigned integer field.  This
   field indicates the current length of the egress interface queue of
   the interface from where the packet is forwarded out.  The queue
   depth is expressed as the current amount of memory buffers used by
   the queue (a packet could consume one or more memory buffers,
   depending on its size).

An existing function (i.e., qdisc_qstats_qlen_backlog) is used to
retrieve the current queue length without reinventing the wheel. Any
comment on that?

Right now, the number of skb's (qlen) is returned, which is not totally
correct compared to what the draft says: "a packet could consume one or
more memory buffers". Any idea on a solution to take this into account?

Note: it was tested and qlen is increasing when an artificial delay is
added on the egress with tc.

  [1] https://datatracker.ietf.org/doc/html/draft-ietf-ippm-ioam-data#section-5.4.2.7

Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
---
 net/ipv6/ioam6.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/net/ipv6/ioam6.c b/net/ipv6/ioam6.c
index 122a3d47424c..088eb2f877bc 100644
--- a/net/ipv6/ioam6.c
+++ b/net/ipv6/ioam6.c
@@ -13,10 +13,12 @@ 
 #include <linux/ioam6.h>
 #include <linux/ioam6_genl.h>
 #include <linux/rhashtable.h>
+#include <linux/netdevice.h>
 
 #include <net/addrconf.h>
 #include <net/genetlink.h>
 #include <net/ioam6.h>
+#include <net/sch_generic.h>
 
 static void ioam6_ns_release(struct ioam6_namespace *ns)
 {
@@ -717,7 +719,17 @@  static void __ioam6_fill_trace_data(struct sk_buff *skb,
 
 	/* queue depth */
 	if (trace->type.bit6) {
-		*(__be32 *)data = cpu_to_be32(IOAM6_U32_UNAVAILABLE);
+		struct netdev_queue *queue;
+		__u32 qlen, backlog;
+
+		if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) {
+			*(__be32 *)data = cpu_to_be32(IOAM6_U32_UNAVAILABLE);
+		} else {
+			queue = skb_get_tx_queue(skb_dst(skb)->dev, skb);
+			qdisc_qstats_qlen_backlog(queue->qdisc, &qlen, &backlog);
+
+			*(__be32 *)data = cpu_to_be32(qlen);
+		}
 		data += sizeof(__be32);
 	}