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([2402:e280:21c6:671:f16e:2102:25ad:9cdb]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-33e96d497e1sm760952eec.25.2026.09.22.13.59.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Sep 2026 13:59:51 -0700 (PDT) From: "Hemendra M. Naik" To: netdev@vger.kernel.org Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, jiri@resnulli.us, jhs@mojatatu.com, shuah@kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, vishy0777@gmail.com, tahiliani@nitk.edu.in, "Hemendra M. Naik" Subject: [PATCH net-next v8 1/3] net/sched: sch_fq_pie: add per-flow statistics via class ops Date: Wed, 23 Sep 2026 02:29:22 +0530 Message-Id: <20260922205924.32173-2-hemendranaik@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260922205924.32173-1-hemendranaik@gmail.com> References: <20260922205924.32173-1-hemendranaik@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit FQ-PIE schedules independent PIE controllers per flow but exposes no per-flow AQM state. Without class-level statistics there is no way to observe the per-flow drop probability, queue delay, deficit or dequeue rate from userspace. Extend tc_fq_pie_xstats with a type discriminator and tc_fq_pie_cl_stats for per-flow metrics. The nine existing __u32 counters keep their offsets, type is appended at offset 36 and class_stats follows it, growing the structure from 36 to 64 bytes. Wire up fq_pie_class_ops with walk, dump, and dump_stats only so that 'tc -s class show' reports per-flow state (prob, delay, deficit, avg_dq_rate, dq_rate_estimating). Filter attachment callbacks (.tcf_block, .bind_tcf, .unbind_tcf) are omitted on purpose. Derive delay with div_u64() from the full 64-bit nanosecond. Widen avg_dq_rate to u64 before scaling it by PSCHED_TICKS_PER_SEC. Signed-off-by: Hemendra M. Naik Signed-off-by: Vishal Kamath Signed-off-by: Mohit P. Tahiliani --- include/uapi/linux/pkt_sched.h | 16 +++++++ net/sched/sch_fq_pie.c | 86 +++++++++++++++++++++++++++++++++- 2 files changed, 101 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h index 490efd288526..9c0c9787f0c3 100644 --- a/include/uapi/linux/pkt_sched.h +++ b/include/uapi/linux/pkt_sched.h @@ -953,6 +953,20 @@ enum { }; #define TCA_FQ_PIE_MAX (__TCA_FQ_PIE_MAX - 1) +enum { + TCA_FQ_PIE_XSTATS_QDISC, + TCA_FQ_PIE_XSTATS_CLASS, +}; + +struct tc_fq_pie_cl_stats { + __u64 prob; /* current probability */ + __u32 delay; /* current delay in microseconds */ + __s32 deficit; /* number of remaining byte credits */ + __u32 avg_dq_rate; /* current average dq_rate in + * bytes/second + */ + __u32 dq_rate_estimating; /* is avg_dq_rate being calculated? */ +}; struct tc_fq_pie_xstats { __u32 packets_in; /* total number of packets enqueued */ __u32 dropped; /* packets dropped due to fq_pie_action */ @@ -963,6 +977,8 @@ struct tc_fq_pie_xstats { __u32 new_flows_len; /* count of flows in new list */ __u32 old_flows_len; /* count of flows in old list */ __u32 memory_usage; /* total memory across all queues */ + __u32 type; + struct tc_fq_pie_cl_stats class_stats; }; /* CBS */ diff --git a/net/sched/sch_fq_pie.c b/net/sched/sch_fq_pie.c index 5982847df8f8..3a3ef83f328b 100644 --- a/net/sched/sch_fq_pie.c +++ b/net/sched/sch_fq_pie.c @@ -511,7 +511,9 @@ static int fq_pie_dump(struct Qdisc *sch, struct sk_buff *skb) static int fq_pie_dump_stats(struct Qdisc *sch, struct gnet_dump *d) { struct fq_pie_sched_data *q = qdisc_priv(sch); - struct tc_fq_pie_xstats st = { 0 }; + struct tc_fq_pie_xstats st = { + .type = TCA_FQ_PIE_XSTATS_QDISC, + }; struct list_head *pos; sch_tree_lock(sch); @@ -563,7 +565,89 @@ static void fq_pie_destroy(struct Qdisc *sch) kvfree(q->flows); } +static struct Qdisc *fq_pie_leaf(struct Qdisc *sch, unsigned long arg) +{ + return NULL; +} + +static unsigned long fq_pie_find(struct Qdisc *sch, u32 classid) +{ + return 0; +} + +static int fq_pie_dump_class(struct Qdisc *sch, unsigned long cl, + struct sk_buff *skb, struct tcmsg *tcm) +{ + tcm->tcm_handle |= TC_H_MIN(cl); + return 0; +} + +static int fq_pie_dump_class_stats(struct Qdisc *sch, unsigned long cl, + struct gnet_dump *d) +{ + struct fq_pie_sched_data *q = qdisc_priv(sch); + struct gnet_stats_queue qs = { 0 }; + struct tc_fq_pie_xstats xstats; + u32 idx = cl - 1; + + if (idx < q->flows_cnt) { + const struct fq_pie_flow *flow = &q->flows[idx]; + + memset(&xstats, 0, sizeof(xstats)); + xstats.type = TCA_FQ_PIE_XSTATS_CLASS; + xstats.class_stats.prob = + READ_ONCE(flow->vars.prob) << BITS_PER_BYTE; + xstats.class_stats.delay = + div_u64(PSCHED_TICKS2NS(READ_ONCE(flow->vars.qdelay)), + NSEC_PER_USEC); + xstats.class_stats.deficit = READ_ONCE(flow->deficit); + xstats.class_stats.dq_rate_estimating = + READ_ONCE(q->p_params.dq_rate_estimator); + + if (xstats.class_stats.dq_rate_estimating) { + xstats.class_stats.avg_dq_rate = + ((u64)READ_ONCE(flow->vars.avg_dq_rate) + * PSCHED_TICKS_PER_SEC) >> PIE_SCALE; + } + + qs.qlen = READ_ONCE(flow->qlen); + qs.backlog = READ_ONCE(flow->backlog); + } + if (gnet_stats_copy_queue(d, NULL, &qs, qs.qlen) < 0) + return -1; + if (idx < q->flows_cnt) + return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); + return 0; +} + +static void fq_pie_walk(struct Qdisc *sch, struct qdisc_walker *arg) +{ + struct fq_pie_sched_data *q = qdisc_priv(sch); + unsigned int i; + + if (arg->stop) + return; + + for (i = 0; i < q->flows_cnt; i++) { + if (list_empty(&q->flows[i].flowchain)) { + arg->count++; + continue; + } + if (!tc_qdisc_stats_dump(sch, i + 1, arg)) + break; + } +} + +static const struct Qdisc_class_ops fq_pie_class_ops = { + .leaf = fq_pie_leaf, + .find = fq_pie_find, + .dump = fq_pie_dump_class, + .dump_stats = fq_pie_dump_class_stats, + .walk = fq_pie_walk, +}; + static struct Qdisc_ops fq_pie_qdisc_ops __read_mostly = { + .cl_ops = &fq_pie_class_ops, .id = "fq_pie", .priv_size = sizeof(struct fq_pie_sched_data), .enqueue = fq_pie_qdisc_enqueue, -- 2.34.1