include/net/pie.h

0001 /* SPDX-License-Identifier: GPL-2.0-only */
0002 #ifndef __NET_SCHED_PIE_H
0003 #define __NET_SCHED_PIE_H
0004
0005 #include <linux/ktime.h>
0006 #include <linux/skbuff.h>
0007 #include <linux/types.h>
0008 #include <net/inet_ecn.h>
0009 #include <net/pkt_sched.h>
0010
0011 #define MAX_PROB    (U64_MAX >> BITS_PER_BYTE)
0012 #define DTIME_INVALID   U64_MAX
0013 #define QUEUE_THRESHOLD 16384
0014 #define DQCOUNT_INVALID -1
0015 #define PIE_SCALE   8
0016
0017 /**
0018  * struct pie_params - contains pie parameters
0019  * @target:     target delay in pschedtime
0020  * @tudpate:        interval at which drop probability is calculated
0021  * @limit:      total number of packets that can be in the queue
0022  * @alpha:      parameter to control drop probability
0023  * @beta:       parameter to control drop probability
0024  * @ecn:        is ECN marking of packets enabled
0025  * @bytemode:       is drop probability scaled based on pkt size
0026  * @dq_rate_estimator:  is Little's law used for qdelay calculation
0027  */
0028 struct pie_params {
0029     psched_time_t target;
0030     u32 tupdate;
0031     u32 limit;
0032     u32 alpha;
0033     u32 beta;
0034     u8 ecn;
0035     u8 bytemode;
0036     u8 dq_rate_estimator;
0037 };
0038
0039 /**
0040  * struct pie_vars - contains pie variables
0041  * @qdelay:     current queue delay
0042  * @qdelay_old:     queue delay in previous qdelay calculation
0043  * @burst_time:     burst time allowance
0044  * @dq_tstamp:      timestamp at which dq rate was last calculated
0045  * @prob:       drop probability
0046  * @accu_prob:      accumulated drop probability
0047  * @dq_count:       number of bytes dequeued in a measurement cycle
0048  * @avg_dq_rate:    calculated average dq rate
0049  * @backlog_old:    queue backlog during previous qdelay calculation
0050  */
0051 struct pie_vars {
0052     psched_time_t qdelay;
0053     psched_time_t qdelay_old;
0054     psched_time_t burst_time;
0055     psched_time_t dq_tstamp;
0056     u64 prob;
0057     u64 accu_prob;
0058     u64 dq_count;
0059     u32 avg_dq_rate;
0060     u32 backlog_old;
0061 };
0062
0063 /**
0064  * struct pie_stats - contains pie stats
0065  * @packets_in: total number of packets enqueued
0066  * @dropped:    packets dropped due to pie action
0067  * @overlimit:  packets dropped due to lack of space in queue
0068  * @ecn_mark:   packets marked with ECN
0069  * @maxq:   maximum queue size
0070  */
0071 struct pie_stats {
0072     u32 packets_in;
0073     u32 dropped;
0074     u32 overlimit;
0075     u32 ecn_mark;
0076     u32 maxq;
0077 };
0078
0079 /**
0080  * struct pie_skb_cb - contains private skb vars
0081  * @enqueue_time:   timestamp when the packet is enqueued
0082  * @mem_usage:      size of the skb during enqueue
0083  */
0084 struct pie_skb_cb {
0085     psched_time_t enqueue_time;
0086     u32 mem_usage;
0087 };
0088
0089 static inline void pie_params_init(struct pie_params *params)
0090 {
0091     params->target = PSCHED_NS2TICKS(15 * NSEC_PER_MSEC);   /* 15 ms */
0092     params->tupdate = usecs_to_jiffies(15 * USEC_PER_MSEC); /* 15 ms */
0093     params->limit = 1000;
0094     params->alpha = 2;
0095     params->beta = 20;
0096     params->ecn = false;
0097     params->bytemode = false;
0098     params->dq_rate_estimator = false;
0099 }
0100
0101 static inline void pie_vars_init(struct pie_vars *vars)
0102 {
0103     vars->burst_time = PSCHED_NS2TICKS(150 * NSEC_PER_MSEC); /* 150 ms */
0104     vars->dq_tstamp = DTIME_INVALID;
0105     vars->accu_prob = 0;
0106     vars->dq_count = DQCOUNT_INVALID;
0107     vars->avg_dq_rate = 0;
0108 }
0109
0110 static inline struct pie_skb_cb *get_pie_cb(const struct sk_buff *skb)
0111 {
0112     qdisc_cb_private_validate(skb, sizeof(struct pie_skb_cb));
0113     return (struct pie_skb_cb *)qdisc_skb_cb(skb)->data;
0114 }
0115
0116 static inline psched_time_t pie_get_enqueue_time(const struct sk_buff *skb)
0117 {
0118     return get_pie_cb(skb)->enqueue_time;
0119 }
0120
0121 static inline void pie_set_enqueue_time(struct sk_buff *skb)
0122 {
0123     get_pie_cb(skb)->enqueue_time = psched_get_time();
0124 }
0125
0126 bool pie_drop_early(struct Qdisc *sch, struct pie_params *params,
0127             struct pie_vars *vars, u32 backlog, u32 packet_size);
0128
0129 void pie_process_dequeue(struct sk_buff *skb, struct pie_params *params,
0130              struct pie_vars *vars, u32 backlog);
0131
0132 void pie_calculate_probability(struct pie_params *params, struct pie_vars *vars,
0133                    u32 backlog);
0134
0135 #endif