diff mbox series

[v4,net-next,05/11] net/sched: taprio: dump class stats for the actual q->qdiscs[]

Message ID 20230807193324.4128292-6-vladimir.oltean@nxp.com (mailing list archive)
State Accepted
Commit 665338b2a7a0139337d1f85be65ed16e487f84c1
Delegated to: Netdev Maintainers
Headers show
Series Improve the taprio qdisc's relationship with its children | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1330 this patch: 1330
netdev/cc_maintainers warning 3 maintainers not CCed: kuniyu@amazon.com shuah@kernel.org linux-kselftest@vger.kernel.org
netdev/build_clang success Errors and warnings before: 1353 this patch: 1353
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1353 this patch: 1353
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 38 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Vladimir Oltean Aug. 7, 2023, 7:33 p.m. UTC
This makes a difference for the software scheduling mode, where
dev_queue->qdisc_sleeping is the same as the taprio root Qdisc itself,
but when we're talking about what Qdisc and stats get reported for a
traffic class, the root taprio isn't what comes to mind, but q->qdiscs[]
is.

To understand the difference, I've attempted to send 100 packets in
software mode through class 8001:5, and recorded the stats before and
after the change.

Here is before:

$ tc -s class show dev eth0
class taprio 8001:1 root leaf 8001:
 Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:2 root leaf 8001:
 Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:3 root leaf 8001:
 Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:4 root leaf 8001:
 Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:5 root leaf 8001:
 Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:6 root leaf 8001:
 Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:7 root leaf 8001:
 Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:8 root leaf 8001:
 Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0

and here is after:

class taprio 8001:1 root
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:2 root
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:3 root
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:4 root
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:5 root
 Sent 9400 bytes 100 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:6 root
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:7 root
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0
class taprio 8001:8 root leaf 800d:
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 window_drops 0

The most glaring (and expected) difference is that before, all class
stats reported the global stats, whereas now, they really report just
the counters for that traffic class.

Finally, Pedro Tammela points out that there is a tc selftest which
checks specifically which handle do the child Qdiscs corresponding to
each class have. That's changing here - taprio no longer reports
tcm->tcm_info as the same handle "1:" as itself (the root Qdisc), but 0
(the handle of the default pfifo child Qdiscs). Since iproute2 does not
print a child Qdisc handle of 0, adjust the test's expected output.

Link: https://lore.kernel.org/netdev/3b83fcf6-a5e8-26fb-8c8a-ec34ec4c3342@mojatatu.com/
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
v3->v4: none
v2->v3: fix selftest broken by the change
v1->v2:
- reword commit message
- rebase on top of the TAPRIO_CMD_TC_STATS -> TAPRIO_CMD_QUEUE_STATS change

 net/sched/sch_taprio.c                                    | 8 +++-----
 .../selftests/tc-testing/tc-tests/qdiscs/taprio.json      | 2 +-
 2 files changed, 4 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index d5693bd52e93..1cb5e41c0ec7 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -2472,11 +2472,11 @@  static unsigned long taprio_find(struct Qdisc *sch, u32 classid)
 static int taprio_dump_class(struct Qdisc *sch, unsigned long cl,
 			     struct sk_buff *skb, struct tcmsg *tcm)
 {
-	struct netdev_queue *dev_queue = taprio_queue_get(sch, cl);
+	struct Qdisc *child = taprio_leaf(sch, cl);
 
 	tcm->tcm_parent = TC_H_ROOT;
 	tcm->tcm_handle |= TC_H_MIN(cl);
-	tcm->tcm_info = rtnl_dereference(dev_queue->qdisc_sleeping)->handle;
+	tcm->tcm_info = child->handle;
 
 	return 0;
 }
@@ -2486,16 +2486,14 @@  static int taprio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 	__releases(d->lock)
 	__acquires(d->lock)
 {
-	struct netdev_queue *dev_queue = taprio_queue_get(sch, cl);
+	struct Qdisc *child = taprio_leaf(sch, cl);
 	struct tc_taprio_qopt_offload offload = {
 		.cmd = TAPRIO_CMD_QUEUE_STATS,
 		.queue_stats = {
 			.queue = cl - 1,
 		},
 	};
-	struct Qdisc *child;
 
-	child = rtnl_dereference(dev_queue->qdisc_sleeping);
 	if (gnet_stats_copy_basic(d, NULL, &child->bstats, true) < 0 ||
 	    qdisc_qstats_copy(d, child) < 0)
 		return -1;
diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
index 08d4861c2e78..860b55df0d6d 100644
--- a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
@@ -104,7 +104,7 @@ 
         "cmdUnderTest": "$TC qdisc add dev $ETH root handle 1: taprio num_tc 3 map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 queues 1@0 1@0 1@0 base-time 1000000000 sched-entry S 01 300000 flags 0x1 clockid CLOCK_TAI",
         "expExitCode": "0",
         "verifyCmd": "$TC class show dev $ETH",
-        "matchPattern": "class taprio 1:[0-9]+ root leaf 1:",
+        "matchPattern": "class taprio 1:[0-9]+ root",
         "matchCount": "8",
         "teardown": [
             "echo \"1\" > /sys/bus/netdevsim/del_device"