Merge branch 'dualpi2-patch'

Chia-Yu Chang says:

====================
DUALPI2 patch

This patch serise adds DualPI Improved with a Square (DualPI2) with
following features:
 * Supports congestion controls that comply with the Prague requirements
   in RFC9331 (e.g. TCP-Prague)
 * Coupled dual-queue that separates the L4S traffic in a low latency
   queue (L-queue), without harming remaining traffic that is scheduled
   in classic queue (C-queue) due to congestion-coupling using PI2
   as defined in RFC9332
 * Configurable overload strategies
 * Use of sojourn time to reliably estimate queue delay
 * Supports ECN L4S-identifier (IP.ECN==0b*1) to classify traffic into
   respective queues

For more details of DualPI2, please refer IETF RFC9332
(https://datatracker.ietf.org/doc/html/rfc9332).
====================

Link: https://patch.msgid.link/20250722095915.24485-1-chia-yu.chang@nokia-bell-labs.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

Documentation/netlink/specs/tc.yaml

@@ -56,6 +56,23 @@ definitions:
       - tundf
       - tunoam
       - tuncrit
+  -
+    name: dualpi2-drop-overload
+    type: enum
+    entries: [overflow, drop]
+  -
+    name: dualpi2-drop-early
+    type: enum
+    entries: [drop-dequeue, drop-enqueue]
+  -
+    name: dualpi2-ecn-mask
+    type: enum
+    value-start: 1
+    entries: [l4s-ect, cla-ect, any-ect]
+  -
+    name: dualpi2-split-gso
+    type: enum
+    entries: [no-split-gso, split-gso]
   -
     name: tc-stats
     type: struct
@@ -825,6 +842,58 @@ definitions:
       -
         name: drop-overmemory
         type: u32
+  -
+    name: tc-dualpi2-xstats
+    type: struct
+    members:
+      -
+        name: prob
+        type: u32
+        doc: Current base PI probability
+      -
+        name: delay-c
+        type: u32
+        doc: Current C-queue delay in microseconds
+      -
+        name: delay-l
+        type: u32
+        doc: Current L-queue delay in microseconds
+      -
+        name: pkts-in-c
+        type: u32
+        doc: Number of packets enqueued in the C-queue
+      -
+        name: pkts-in-l
+        type: u32
+        doc: Number of packets enqueued in the L-queue
+      -
+        name: maxq
+        type: u32
+        doc: Maximum number of packets seen by the DualPI2
+      -
+        name: ecn-mark
+        type: u32
+        doc: All packets marked with ECN
+      -
+        name: step-mark
+        type: u32
+        doc: Only packets marked with ECN due to L-queue step AQM
+      -
+        name: credit
+        type: s32
+        doc: Current credit value for WRR
+      -
+        name: memory-used
+        type: u32
+        doc: Memory used in bytes by the DualPI2
+      -
+        name: max-memory-used
+        type: u32
+        doc: Maximum memory used in bytes by the DualPI2
+      -
+        name: memory-limit
+        type: u32
+        doc: Memory limit in bytes
   -
     name: tc-fq-pie-xstats
     type: struct
@@ -848,7 +917,7 @@ definitions:
       -
         name: ecn-mark
         type: u32
-        doc: Packets marked with ecn
+        doc: Packets marked with ECN
       -
         name: new-flow-count
         type: u32
@@ -991,7 +1060,7 @@ definitions:
       -
         name: ecn-mark
         type: u32
-        doc: Packets marked with ecn
+        doc: Packets marked with ECN
   -
     name: tc-red-xstats
     type: struct
@@ -2284,6 +2353,78 @@ attribute-sets:
       -
         name: quantum
         type: u32
+  -
+    name: dualpi2-attrs
+    name-prefix: tca-dualpi2-
+    attributes:
+      -
+        name: limit
+        type: u32
+        doc: Limit of total number of packets in queue
+      -
+        name: memory-limit
+        type: u32
+        doc: Memory limit of total number of packets in queue
+      -
+        name: target
+        type: u32
+        doc: Classic target delay in microseconds
+      -
+        name: tupdate
+        type: u32
+        doc: Drop probability update interval time in microseconds
+      -
+        name: alpha
+        type: u32
+        doc: Integral gain factor in Hz for PI controller
+      -
+        name: beta
+        type: u32
+        doc: Proportional gain factor in Hz for PI controller
+      -
+        name: step-thresh-pkts
+        type: u32
+        doc: L4S step marking threshold in packets
+      -
+        name: step-thresh-us
+        type: u32
+        doc: L4S Step marking threshold in microseconds
+      -
+        name: min-qlen-step
+        type: u32
+        doc: Packets enqueued to the L-queue can apply the step threshold
+             when the queue length of L-queue is larger than this value.
+             (0 is recommended)
+      -
+        name: coupling
+        type: u8
+        doc: Probability coupling factor between Classic and L4S
+             (2 is recommended)
+      -
+        name: drop-overload
+        type: u8
+        doc: Control the overload strategy (drop to preserve latency or
+             let the queue overflow)
+        enum: dualpi2-drop-overload
+      -
+        name: drop-early
+        type: u8
+        doc: Decide where the Classic packets are PI-based dropped or marked
+        enum: dualpi2-drop-early
+      -
+        name: c-protection
+        type: u8
+        doc: Classic WRR weight in percentage (from 0 to 100)
+      -
+        name: ecn-mask
+        type: u8
+        doc: Configure the L-queue ECN classifier
+        enum: dualpi2-ecn-mask
+      -
+        name: split-gso
+        type: u8
+        doc: Split aggregated skb or not
+        enum: dualpi2-split-gso
   -
     name: ematch-attrs
     name-prefix: tca-ematch-
@@ -3708,6 +3849,9 @@ sub-messages:
       -
         value: drr
         attribute-set: drr-attrs
+      -
+        value: dualpi2
+        attribute-set: dualpi2-attrs
       -
         value: etf
         attribute-set: etf-attrs
@@ -3875,6 +4019,9 @@ sub-messages:
       -
         value: codel
         fixed-header: tc-codel-xstats
+      -
+        value: dualpi2
+        fixed-header: tc-dualpi2-xstats
       -
         value: fq
         fixed-header: tc-fq-qd-stats

include/net/dropreason-core.h

@@ -126,6 +126,7 @@
 	FN(CANFD_RX_INVALID_FRAME)	\
 	FN(CANXL_RX_INVALID_FRAME)	\
 	FN(PFMEMALLOC)	\
+	FN(DUALPI2_STEP_DROP)		\
 	FNe(MAX)
 
 /**
@@ -604,6 +605,11 @@ enum skb_drop_reason {
 	 * reached a path or socket not eligible for use of memory reserves
 	 */
 	SKB_DROP_REASON_PFMEMALLOC,
+	/**
+	 * @SKB_DROP_REASON_DUALPI2_STEP_DROP: dropped by the step drop
+	 * threshold of DualPI2 qdisc.
+	 */
+	SKB_DROP_REASON_DUALPI2_STEP_DROP,
 	/**
 	 * @SKB_DROP_REASON_MAX: the maximum of core drop reasons, which
 	 * shouldn't be used as a real 'reason' - only for tracing code gen

include/uapi/linux/pkt_sched.h

@@ -1211,4 +1211,72 @@ enum {
 
 #define TCA_ETS_MAX (__TCA_ETS_MAX - 1)
 
+/* DUALPI2 */
+enum tc_dualpi2_drop_overload {
+	TC_DUALPI2_DROP_OVERLOAD_OVERFLOW = 0,
+	TC_DUALPI2_DROP_OVERLOAD_DROP = 1,
+	__TCA_DUALPI2_DROP_OVERLOAD_MAX,
+};
+#define TCA_DUALPI2_DROP_OVERLOAD_MAX (__TCA_DUALPI2_DROP_OVERLOAD_MAX - 1)
+
+enum tc_dualpi2_drop_early {
+	TC_DUALPI2_DROP_EARLY_DROP_DEQUEUE = 0,
+	TC_DUALPI2_DROP_EARLY_DROP_ENQUEUE = 1,
+	__TCA_DUALPI2_DROP_EARLY_MAX,
+};
+#define TCA_DUALPI2_DROP_EARLY_MAX (__TCA_DUALPI2_DROP_EARLY_MAX - 1)
+
+enum tc_dualpi2_ecn_mask {
+	TC_DUALPI2_ECN_MASK_L4S_ECT = 1,
+	TC_DUALPI2_ECN_MASK_CLA_ECT = 2,
+	TC_DUALPI2_ECN_MASK_ANY_ECT = 3,
+	__TCA_DUALPI2_ECN_MASK_MAX,
+};
+#define TCA_DUALPI2_ECN_MASK_MAX (__TCA_DUALPI2_ECN_MASK_MAX - 1)
+
+enum tc_dualpi2_split_gso {
+	TC_DUALPI2_SPLIT_GSO_NO_SPLIT_GSO = 0,
+	TC_DUALPI2_SPLIT_GSO_SPLIT_GSO = 1,
+	__TCA_DUALPI2_SPLIT_GSO_MAX,
+};
+#define TCA_DUALPI2_SPLIT_GSO_MAX (__TCA_DUALPI2_SPLIT_GSO_MAX - 1)
+
+enum {
+	TCA_DUALPI2_UNSPEC,
+	TCA_DUALPI2_LIMIT,		/* Packets */
+	TCA_DUALPI2_MEMORY_LIMIT,	/* Bytes */
+	TCA_DUALPI2_TARGET,		/* us */
+	TCA_DUALPI2_TUPDATE,		/* us */
+	TCA_DUALPI2_ALPHA,		/* Hz scaled up by 256 */
+	TCA_DUALPI2_BETA,		/* Hz scaled up by 256 */
+	TCA_DUALPI2_STEP_THRESH_PKTS,	/* Step threshold in packets */
+	TCA_DUALPI2_STEP_THRESH_US,	/* Step threshold in microseconds */
+	TCA_DUALPI2_MIN_QLEN_STEP,	/* Minimum qlen to apply STEP_THRESH */
+	TCA_DUALPI2_COUPLING,		/* Coupling factor between queues */
+	TCA_DUALPI2_DROP_OVERLOAD,	/* Whether to drop on overload */
+	TCA_DUALPI2_DROP_EARLY,		/* Whether to drop on enqueue */
+	TCA_DUALPI2_C_PROTECTION,	/* Percentage */
+	TCA_DUALPI2_ECN_MASK,		/* L4S queue classification mask */
+	TCA_DUALPI2_SPLIT_GSO,		/* Split GSO packets at enqueue */
+	TCA_DUALPI2_PAD,
+	__TCA_DUALPI2_MAX
+};
+
+#define TCA_DUALPI2_MAX   (__TCA_DUALPI2_MAX - 1)
+
+struct tc_dualpi2_xstats {
+	__u32 prob;		/* current probability */
+	__u32 delay_c;		/* current delay in C queue */
+	__u32 delay_l;		/* current delay in L queue */
+	__u32 packets_in_c;	/* number of packets enqueued in C queue */
+	__u32 packets_in_l;	/* number of packets enqueued in L queue */
+	__u32 maxq;		/* maximum queue size */
+	__u32 ecn_mark;		/* packets marked with ecn*/
+	__u32 step_marks;	/* ECN marks due to the step AQM */
+	__s32 credit;		/* current c_protection credit */
+	__u32 memory_used;	/* Memory used by both queues */
+	__u32 max_memory_used;	/* Maximum used memory */
+	__u32 memory_limit;	/* Memory limit of both queues */
+};
+
 #endif

net/sched/Kconfig

@@ -415,6 +415,18 @@ config NET_SCH_BPF
 
 	  If unsure, say N.
 
+config NET_SCH_DUALPI2
+	tristate "Dual Queue PI Square (DUALPI2) scheduler"
+	help
+	  Say Y here if you want to use the Dual Queue Proportional Integral
+	  Controller Improved with a Square scheduling algorithm.
+	  For more information, please see https://tools.ietf.org/html/rfc9332
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called sch_dualpi2.
+
+	  If unsure, say N.
+
 menuconfig NET_SCH_DEFAULT
 	bool "Allow override default queue discipline"
 	help

net/sched/Makefile

@@ -63,6 +63,7 @@ obj-$(CONFIG_NET_SCH_CBS)	+= sch_cbs.o
 obj-$(CONFIG_NET_SCH_ETF)	+= sch_etf.o
 obj-$(CONFIG_NET_SCH_TAPRIO)	+= sch_taprio.o
 obj-$(CONFIG_NET_SCH_BPF)	+= bpf_qdisc.o
+obj-$(CONFIG_NET_SCH_DUALPI2)	+= sch_dualpi2.o
 
 obj-$(CONFIG_NET_CLS_U32)	+= cls_u32.o
 obj-$(CONFIG_NET_CLS_ROUTE4)	+= cls_route.o