1 /* SPDX-License-Identifier: GPL-2.0-only */
2 #ifndef __NET_SCHED_PIE_H
3 #define __NET_SCHED_PIE_H
4 
5 #include <linux/ktime.h>
6 #include <linux/skbuff.h>
7 #include <linux/types.h>
8 #include <net/inet_ecn.h>
9 #include <net/pkt_sched.h>
10 
11 #define MAX_PROB	(U64_MAX >> BITS_PER_BYTE)
12 #define DTIME_INVALID	U64_MAX
13 #define QUEUE_THRESHOLD	16384
14 #define DQCOUNT_INVALID	-1
15 #define PIE_SCALE	8
16 
17 /**
18  * struct pie_params - contains pie parameters
19  * @target:		target delay in pschedtime
20  * @tudpate:		interval at which drop probability is calculated
21  * @limit:		total number of packets that can be in the queue
22  * @alpha:		parameter to control drop probability
23  * @beta:		parameter to control drop probability
24  * @ecn:		is ECN marking of packets enabled
25  * @bytemode:		is drop probability scaled based on pkt size
26  * @dq_rate_estimator:	is Little's law used for qdelay calculation
27  */
28 struct pie_params {
29 	psched_time_t target;
30 	u32 tupdate;
31 	u32 limit;
32 	u32 alpha;
33 	u32 beta;
34 	u8 ecn;
35 	u8 bytemode;
36 	u8 dq_rate_estimator;
37 };
38 
39 /**
40  * struct pie_vars - contains pie variables
41  * @qdelay:		current queue delay
42  * @qdelay_old:		queue delay in previous qdelay calculation
43  * @burst_time:		burst time allowance
44  * @dq_tstamp:		timestamp at which dq rate was last calculated
45  * @prob:		drop probability
46  * @accu_prob:		accumulated drop probability
47  * @dq_count:		number of bytes dequeued in a measurement cycle
48  * @avg_dq_rate:	calculated average dq rate
49  * @backlog_old:	queue backlog during previous qdelay calculation
50  */
51 struct pie_vars {
52 	psched_time_t qdelay;
53 	psched_time_t qdelay_old;
54 	psched_time_t burst_time;
55 	psched_time_t dq_tstamp;
56 	u64 prob;
57 	u64 accu_prob;
58 	u64 dq_count;
59 	u32 avg_dq_rate;
60 	u32 backlog_old;
61 };
62 
63 /**
64  * struct pie_stats - contains pie stats
65  * @packets_in:	total number of packets enqueued
66  * @dropped:	packets dropped due to pie action
67  * @overlimit:	packets dropped due to lack of space in queue
68  * @ecn_mark:	packets marked with ECN
69  * @maxq:	maximum queue size
70  */
71 struct pie_stats {
72 	u32 packets_in;
73 	u32 dropped;
74 	u32 overlimit;
75 	u32 ecn_mark;
76 	u32 maxq;
77 };
78 
79 /**
80  * struct pie_skb_cb - contains private skb vars
81  * @enqueue_time:	timestamp when the packet is enqueued
82  * @mem_usage:		size of the skb during enqueue
83  */
84 struct pie_skb_cb {
85 	psched_time_t enqueue_time;
86 	u32 mem_usage;
87 };
88 
pie_params_init(struct pie_params * params)89 static inline void pie_params_init(struct pie_params *params)
90 {
91 	params->target = PSCHED_NS2TICKS(15 * NSEC_PER_MSEC);	/* 15 ms */
92 	params->tupdate = usecs_to_jiffies(15 * USEC_PER_MSEC);	/* 15 ms */
93 	params->limit = 1000;
94 	params->alpha = 2;
95 	params->beta = 20;
96 	params->ecn = false;
97 	params->bytemode = false;
98 	params->dq_rate_estimator = false;
99 }
100 
pie_vars_init(struct pie_vars * vars)101 static inline void pie_vars_init(struct pie_vars *vars)
102 {
103 	vars->burst_time = PSCHED_NS2TICKS(150 * NSEC_PER_MSEC); /* 150 ms */
104 	vars->dq_tstamp = DTIME_INVALID;
105 	vars->accu_prob = 0;
106 	vars->dq_count = DQCOUNT_INVALID;
107 	vars->avg_dq_rate = 0;
108 }
109 
get_pie_cb(const struct sk_buff * skb)110 static inline struct pie_skb_cb *get_pie_cb(const struct sk_buff *skb)
111 {
112 	qdisc_cb_private_validate(skb, sizeof(struct pie_skb_cb));
113 	return (struct pie_skb_cb *)qdisc_skb_cb(skb)->data;
114 }
115 
pie_get_enqueue_time(const struct sk_buff * skb)116 static inline psched_time_t pie_get_enqueue_time(const struct sk_buff *skb)
117 {
118 	return get_pie_cb(skb)->enqueue_time;
119 }
120 
pie_set_enqueue_time(struct sk_buff * skb)121 static inline void pie_set_enqueue_time(struct sk_buff *skb)
122 {
123 	get_pie_cb(skb)->enqueue_time = psched_get_time();
124 }
125 
126 bool pie_drop_early(struct Qdisc *sch, struct pie_params *params,
127 		    struct pie_vars *vars, u32 backlog, u32 packet_size);
128 
129 void pie_process_dequeue(struct sk_buff *skb, struct pie_params *params,
130 			 struct pie_vars *vars, u32 backlog);
131 
132 void pie_calculate_probability(struct pie_params *params, struct pie_vars *vars,
133 			       u32 backlog);
134 
135 #endif
136