Re: [PATCH v15 net-next 2/5] sched: Dump configuration and statistics of dualpi2 qdisc

On 5/9/25 11:47 PM, chia-yu.chang@nokia-bell-labs.com wrote:

From: Chia-Yu Chang chia-yu.chang@nokia-bell-labs.com

The configuration and statistics dump of the DualPI2 Qdisc provides information related to both queues, such as packet numbers and queuing delays in the L-queue and C-queue, as well as general information such as probability value, WRR credits, memory usage, packet marking counters, max queue size, etc.

The following patch includes enqueue/dequeue for DualPI2.

Signed-off-by: Chia-Yu Chang chia-yu.chang@nokia-bell-labs.com

include/uapi/linux/pkt_sched.h | 15 ++++++ net/sched/sch_dualpi2.c | 86 ++++++++++++++++++++++++++++++++++ 2 files changed, 101 insertions(+)

diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h index f897819b1624..bc248fd49f6f 100644 --- a/include/uapi/linux/pkt_sched.h +++ b/include/uapi/linux/pkt_sched.h @@ -1263,4 +1263,19 @@ enum { #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 of both queues */
• __u32 max_memory_used; /* Maximum used memory */
• __u32 memory_limit; /* Memory limit of both queues */

+};

#endif diff --git a/net/sched/sch_dualpi2.c b/net/sched/sch_dualpi2.c index 4bc75c0b3436..81e238b5aaa9 100644 --- a/net/sched/sch_dualpi2.c +++ b/net/sched/sch_dualpi2.c @@ -123,6 +123,14 @@ static u32 dualpi2_scale_alpha_beta(u32 param) return tmp; } +static u32 dualpi2_unscale_alpha_beta(u32 param) +{

• u64 tmp = ((u64)param * NSEC_PER_SEC << ALPHA_BETA_SCALING);
• do_div(tmp, MAX_PROB);
• return tmp;

+}

static ktime_t next_pi2_timeout(struct dualpi2_sched_data *q) { return ktime_add_ns(ktime_get_ns(), q->pi2_tupdate); @@ -440,6 +448,82 @@ static int dualpi2_init(struct Qdisc *sch, struct nlattr *opt, return 0; } +static u32 convert_ns_to_usec(u64 ns) +{

• do_div(ns, NSEC_PER_USEC);
• return ns;

+}

+static int dualpi2_dump(struct Qdisc *sch, struct sk_buff *skb) +{

• struct dualpi2_sched_data *q = qdisc_priv(sch);
• struct nlattr *opts;
• opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
• if (!opts)

• goto nla_put_failure;
  

• if (nla_put_u32(skb, TCA_DUALPI2_LIMIT, READ_ONCE(sch->limit)) ||

•    nla_put_u32(skb, TCA_DUALPI2_MEMORY_LIMIT,
  

• 	READ_ONCE(q->memory_limit)) ||
  

•    nla_put_u32(skb, TCA_DUALPI2_TARGET,
  

• 	convert_ns_to_usec(READ_ONCE(q->pi2_target))) ||
  

•    nla_put_u32(skb, TCA_DUALPI2_TUPDATE,
  

• 	convert_ns_to_usec(READ_ONCE(q->pi2_tupdate))) ||
  

•    nla_put_u32(skb, TCA_DUALPI2_ALPHA,
  

• 	dualpi2_unscale_alpha_beta(READ_ONCE(q->pi2_alpha))) ||
  

•    nla_put_u32(skb, TCA_DUALPI2_BETA,
  

• 	dualpi2_unscale_alpha_beta(READ_ONCE(q->pi2_beta))) ||
  

•    nla_put_u32(skb, TCA_DUALPI2_STEP_THRESH,
  

• 	READ_ONCE(q->step_in_packets) ?
  

• 	READ_ONCE(q->step_thresh) :
  

• 	convert_ns_to_usec(READ_ONCE(q->step_thresh))) ||
  

•    nla_put_u32(skb, TCA_DUALPI2_MIN_QLEN_STEP,
  

• 	READ_ONCE(q->min_qlen_step)) ||
  

•    nla_put_u8(skb, TCA_DUALPI2_COUPLING,
  

•        READ_ONCE(q->coupling_factor)) ||
  

•    nla_put_u8(skb, TCA_DUALPI2_DROP_OVERLOAD,
  

•        READ_ONCE(q->drop_overload)) ||
  

•    (READ_ONCE(q->step_in_packets) &&
  

•     nla_put_flag(skb, TCA_DUALPI2_STEP_PACKETS)) ||
  

•    nla_put_u8(skb, TCA_DUALPI2_DROP_EARLY,
  

•        READ_ONCE(q->drop_early)) ||
  

•    nla_put_u8(skb, TCA_DUALPI2_C_PROTECTION,
  

•        READ_ONCE(q->c_protection_wc)) ||
  

•    nla_put_u8(skb, TCA_DUALPI2_ECN_MASK, READ_ONCE(q->ecn_mask)) ||
  

•    nla_put_u8(skb, TCA_DUALPI2_SPLIT_GSO, READ_ONCE(q->split_gso)))
  

• goto nla_put_failure;
  

• return nla_nest_end(skb, opts);

+nla_put_failure:

• nla_nest_cancel(skb, opts);
• return -1;

+}

+static int dualpi2_dump_stats(struct Qdisc *sch, struct gnet_dump *d) +{

• struct dualpi2_sched_data *q = qdisc_priv(sch);
• struct tc_dualpi2_xstats st = {

• .prob			= READ_ONCE(q->pi2_prob),
  

• .packets_in_c		= q->packets_in_c,
  

• .packets_in_l		= q->packets_in_l,
  

• .maxq			= q->maxq,
  

• .ecn_mark		= q->ecn_mark,
  

• .credit			= q->c_protection_credit,
  

• .step_marks		= q->step_marks,
  

• .memory_used		= q->memory_used,
  

• .max_memory_used	= q->max_memory_used,
  

• .memory_limit		= q->memory_limit,
  

• };
• u64 qc, ql;
• get_queue_delays(q, &qc, &ql);
• st.delay_l = convert_ns_to_usec(ql);
• st.delay_c = convert_ns_to_usec(qc);

Both delay_l and delay_c are u32. AFAICS, on pathological situations both could overrun.

/P