FreeBSD/Linux Kernel Cross Reference
sys/netinet/tcp_stacks/tcp_rack.h

     /*-
      * Copyright (c) 2016-2020 Netflix, Inc.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
      * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    
    #ifndef _NETINET_TCP_RACK_H_
    #define _NETINET_TCP_RACK_H_
    
    #define RACK_ACKED          0x000001/* The remote endpoint acked this */
    #define RACK_TO_REXT        0x000002/* A timeout occurred on this sendmap entry */
    #define RACK_DEFERRED       0x000004/* We can't use this for RTT calc - not used */
    #define RACK_OVERMAX        0x000008/* We have more retran's then we can fit */
    #define RACK_SACK_PASSED    0x000010/* A sack was done above this block */
    #define RACK_WAS_SACKPASS   0x000020/* We retransmitted due to SACK pass */
    #define RACK_HAS_FIN        0x000040/* segment is sent with fin */
    #define RACK_TLP            0x000080/* segment sent as tail-loss-probe */
    #define RACK_RWND_COLLAPSED 0x000100/* The peer collapsed the rwnd on the segment */
    #define RACK_APP_LIMITED    0x000200/* We went app limited after this send */
    #define RACK_WAS_ACKED      0x000400/* a RTO undid the ack, but it already had a rtt calc done */
    #define RACK_HAS_SYN        0x000800/* SYN is on this guy */
    #define RACK_SENT_W_DSACK   0x001000/* Sent with a dsack */
    #define RACK_SENT_SP        0x002000/* sent in slow path */
    #define RACK_SENT_FP        0x004000/* sent in fast path */
    #define RACK_HAD_PUSH       0x008000/* Push was sent on original send */
    #define RACK_MUST_RXT       0x010000/* We must retransmit this rsm (non-sack/mtu chg)*/
    #define RACK_NUM_OF_RETRANS 3
    
    #define RACK_INITIAL_RTO 1000000 /* 1 second in microseconds */
    
    #define RACK_REQ_AVG 3  /* Must be less than 256 */
    
    struct rack_sendmap {
            TAILQ_ENTRY(rack_sendmap) r_tnext;      /* Time of transmit based next */
            uint32_t r_start;       /* Sequence number of the segment */
            uint32_t r_end;         /* End seq, this is 1 beyond actually */
            uint32_t r_rtr_bytes;   /* How many bytes have been retransmitted */
            uint32_t r_flags : 24,  /* Flags as defined above */
                     r_rtr_cnt : 8; /* Retran count, index this -1 to get time */
            struct mbuf *m;
            uint32_t soff;
            uint32_t orig_m_len;
            uint32_t r_nseq_appl;   /* If this one is app limited, this is the nxt seq limited */
            uint8_t r_dupack;       /* Dup ack count */
            uint8_t r_in_tmap;      /* Flag to see if its in the r_tnext array */
            uint8_t r_limit_type;   /* is this entry counted against a limit? */
            uint8_t r_just_ret : 1, /* After sending, the next pkt was just returned, i.e. limited  */
                    r_one_out_nr : 1,       /* Special case 1 outstanding and not in recovery */
                    r_no_rtt_allowed : 1, /* No rtt measurement allowed */
                    r_hw_tls : 1,
                    r_avail : 4;
            uint64_t r_tim_lastsent[RACK_NUM_OF_RETRANS];
            uint64_t r_ack_arrival; /* This is the time of ack-arrival (if SACK'd) */
            RB_ENTRY(rack_sendmap) r_next;          /* RB Tree next */
            uint32_t r_fas;         /* Flight at send */
    };
    
    struct deferred_opt_list {
            TAILQ_ENTRY(deferred_opt_list) next;
            int optname;
            uint64_t optval;
    };
    
    /*
     * Timestamps in the rack sendmap are now moving to be
     * uint64_t's. This means that if you want a uint32_t
     * usec timestamp (the old usecond timestamp) you simply have
     * to cast it to uint32_t. The reason we do this is not for
     * wrap, but we need to get back, at times, to the millisecond
     * timestamp that is used in the TSTMP option. To do this we
     * can use the rack_ts_to_msec() inline below which can take
     * the 64bit ts and make into the correct timestamp millisecond
     * wise. Thats not possible with the 32bit usecond timestamp since
     * the seconds wrap too quickly to cover all bases.
     *
     * There are quite a few places in rack where I simply cast
     * back to uint32_t and then end up using the TSTMP_XX()
     * macros. This is ok, but we could do simple compares if
    * we ever decided to move all of those variables to 64 bits
    * as well.
    */
   
   inline uint64_t
   rack_to_usec_ts(struct timeval *tv)
   {
           return ((tv->tv_sec * HPTS_USEC_IN_SEC) + tv->tv_usec);
   }
   
   inline uint32_t
   rack_ts_to_msec(uint64_t ts)
   {
           return((uint32_t)(ts / HPTS_MSEC_IN_SEC));
   }
   
   
   RB_HEAD(rack_rb_tree_head, rack_sendmap);
   TAILQ_HEAD(rack_head, rack_sendmap);
   TAILQ_HEAD(def_opt_head, deferred_opt_list);
   
   /* Map change logging */
   #define MAP_MERGE       0x01
   #define MAP_SPLIT       0x02
   #define MAP_NEW         0x03
   #define MAP_SACK_M1     0x04
   #define MAP_SACK_M2     0x05
   #define MAP_SACK_M3     0x06
   #define MAP_SACK_M4     0x07
   #define MAP_SACK_M5     0x08
   #define MAP_FREE        0x09
   #define MAP_TRIM_HEAD   0x0a
   
   #define RACK_LIMIT_TYPE_SPLIT   1
   
   /*
    * We use the rate sample structure to
    * assist in single sack/ack rate and rtt
    * calculation. In the future we will expand
    * this in BBR to do forward rate sample
    * b/w estimation.
    */
   #define RACK_RTT_EMPTY 0x00000001       /* Nothing yet stored in RTT's */
   #define RACK_RTT_VALID 0x00000002       /* We have at least one valid RTT */
   struct rack_rtt_sample {
           uint32_t rs_flags;
           uint32_t rs_rtt_lowest;
           uint32_t rs_rtt_highest;
           uint32_t rs_rtt_cnt;
           uint32_t rs_us_rtt;
           int32_t  confidence;
           uint64_t rs_rtt_tot;
           uint16_t rs_us_rtrcnt;
   };
   
   #define RACK_LOG_TYPE_ACK       0x01
   #define RACK_LOG_TYPE_OUT       0x02
   #define RACK_LOG_TYPE_TO        0x03
   #define RACK_LOG_TYPE_ALLOC     0x04
   #define RACK_LOG_TYPE_FREE      0x05
   
   /*
    * Magic numbers for logging timeout events if the
    * logging is enabled.
    */
   #define RACK_TO_FRM_TMR  1
   #define RACK_TO_FRM_TLP  2
   #define RACK_TO_FRM_RACK 3
   #define RACK_TO_FRM_KEEP 4
   #define RACK_TO_FRM_PERSIST 5
   #define RACK_TO_FRM_DELACK 6
   
   struct rack_opts_stats {
           uint64_t tcp_rack_tlp_reduce;
           uint64_t tcp_rack_pace_always;
           uint64_t tcp_rack_pace_reduce;
           uint64_t tcp_rack_max_seg;
           uint64_t tcp_rack_prr_sendalot;
           uint64_t tcp_rack_min_to;
           uint64_t tcp_rack_early_seg;
           uint64_t tcp_rack_reord_thresh;
           uint64_t tcp_rack_reord_fade;
           uint64_t tcp_rack_tlp_thresh;
           uint64_t tcp_rack_pkt_delay;
           uint64_t tcp_rack_tlp_inc_var;
           uint64_t tcp_tlp_use;
           uint64_t tcp_rack_idle_reduce;
           uint64_t tcp_rack_idle_reduce_high;
           uint64_t rack_no_timer_in_hpts;
           uint64_t tcp_rack_min_pace_seg;
           uint64_t tcp_rack_pace_rate_ca;
           uint64_t tcp_rack_rr;
           uint64_t tcp_rack_do_detection;
           uint64_t tcp_rack_rrr_no_conf_rate;
           uint64_t tcp_initial_rate;
           uint64_t tcp_initial_win;
           uint64_t tcp_hdwr_pacing;
           uint64_t tcp_gp_inc_ss;
           uint64_t tcp_gp_inc_ca;
           uint64_t tcp_gp_inc_rec;
           uint64_t tcp_rack_force_max_seg;
           uint64_t tcp_rack_pace_rate_ss;
           uint64_t tcp_rack_pace_rate_rec;
           /* Temp counters for dsack */
           uint64_t tcp_sack_path_1;
           uint64_t tcp_sack_path_2a;
           uint64_t tcp_sack_path_2b;
           uint64_t tcp_sack_path_3;
           uint64_t tcp_sack_path_4;
           /* non temp counters */
           uint64_t tcp_rack_scwnd;
           uint64_t tcp_rack_noprr;
           uint64_t tcp_rack_cfg_rate;
           uint64_t tcp_timely_dyn;
           uint64_t tcp_rack_mbufq;
           uint64_t tcp_fillcw;
           uint64_t tcp_npush;
           uint64_t tcp_lscwnd;
           uint64_t tcp_profile;
           uint64_t tcp_hdwr_rate_cap;
           uint64_t tcp_pacing_rate_cap;
           uint64_t tcp_pacing_up_only;
           uint64_t tcp_use_cmp_acks;
           uint64_t tcp_rack_abc_val;
           uint64_t tcp_rec_abc_val;
           uint64_t tcp_rack_measure_cnt;
           uint64_t tcp_rack_delayed_ack;
           uint64_t tcp_rack_rtt_use;
           uint64_t tcp_data_after_close;
           uint64_t tcp_defer_opt;
           uint64_t tcp_rack_fastrsm_hack;
           uint64_t tcp_rack_beta;
           uint64_t tcp_rack_beta_ecn;
           uint64_t tcp_rack_timer_slop;
           uint64_t tcp_rack_dsack_opt;
   };
   
   /* RTT shrink reasons */
   #define RACK_RTTS_INIT     0
   #define RACK_RTTS_NEWRTT   1
   #define RACK_RTTS_EXITPROBE 2
   #define RACK_RTTS_ENTERPROBE 3
   #define RACK_RTTS_REACHTARGET 4
   #define RACK_RTTS_SEEHBP 5
   #define RACK_RTTS_NOBACKOFF 6
   #define RACK_RTTS_SAFETY 7
   
   #define RACK_USE_BEG 1
   #define RACK_USE_END 2
   #define RACK_USE_END_OR_THACK 3
   
   #define TLP_USE_ID      1       /* Internet draft behavior */
   #define TLP_USE_TWO_ONE 2       /* Use 2.1 behavior */
   #define TLP_USE_TWO_TWO 3       /* Use 2.2 behavior */
   #define RACK_MIN_BW 8000        /* 64kbps in Bps */
   
   /* Rack quality indicators for GPUT measurements */
   #define RACK_QUALITY_NONE       0       /* No quality stated */
   #define RACK_QUALITY_HIGH       1       /* A normal measurement of a GP RTT */
   #define RACK_QUALITY_APPLIMITED 2       /* An app limited case that may be of lower quality */
   #define RACK_QUALITY_PERSIST    3       /* A measurement where we went into persists */
   #define RACK_QUALITY_PROBERTT   4       /* A measurement where we went into or exited probe RTT */
   #define RACK_QUALITY_ALLACKED   5       /* All data is now acknowledged */
   
   /*********************/
   /* Rack Trace points */
   /*********************/
   /*
    * Rack trace points are interesting points within
    * the rack code that the author/debugger may want
    * to have BB logging enabled if we hit that point.
    * In order to enable a trace point you set the
    * sysctl var net.inet.tcp.<stack>.tp.number to
    * one of the numbers listed below. You also
    * must make sure net.inet.tcp.<stack>.tp.bbmode is
    * non-zero, the default is 4 for continuous tracing.
    * You also set in the number of connections you want
    * have get BB logs in net.inet.tcp.<stack>.tp.count.
    *
    * Count will decrement every time BB logging is assigned
    * to a connection that hit your tracepoint.
    *
    * You can enable all trace points by setting the number
    * to 0xffffffff. You can disable all trace points by
    * setting number to zero (or count to 0).
    *
    * Below are the enumerated list of tracepoints that
    * have currently been defined in the code. Add more
    * as you add a call to rack_trace_point(rack, <name>);
    * where <name> is defined below.
    */
   #define RACK_TP_HWENOBUF        0x00000001      /* When we are doing hardware pacing and hit enobufs */
   #define RACK_TP_ENOBUF          0x00000002      /* When we hit enobufs with software pacing */
   #define RACK_TP_COLLAPSED_WND   0x00000003      /* When a peer to collapses its rwnd on us */
   #define RACK_TP_COLLAPSED_RXT   0x00000004      /* When we actually retransmit a collapsed window rsm */
   
   #define MIN_GP_WIN 6    /* We need at least 6 MSS in a GP measurement */
   #ifdef _KERNEL
   #define RACK_OPTS_SIZE (sizeof(struct rack_opts_stats)/sizeof(uint64_t))
   extern counter_u64_t rack_opts_arry[RACK_OPTS_SIZE];
   #define RACK_OPTS_ADD(name, amm) counter_u64_add(rack_opts_arry[(offsetof(struct rack_opts_stats, name)/sizeof(uint64_t))], (amm))
   #define RACK_OPTS_INC(name) RACK_OPTS_ADD(name, 1)
   #endif
   /*
    * As we get each SACK we wade through the
    * rc_map and mark off what is acked.
    * We also increment rc_sacked as well.
    *
    * We also pay attention to missing entries
    * based on the time and possibly mark them
    * for retransmit. If we do and we are not already
    * in recovery we enter recovery. In doing
    * so we claer prr_delivered/holes_rxt and prr_sent_dur_rec.
    * We also setup rc_next/rc_snd_nxt/rc_send_end so
    * we will know where to send from. When not in
    * recovery rc_next will be NULL and rc_snd_nxt should
    * equal snd_max.
    *
    * Whenever we retransmit from recovery we increment
    * rc_holes_rxt as we retran a block and mark it as retransmitted
    * with the time it was sent. During non-recovery sending we
    * add to our map and note the time down of any send expanding
    * the rc_map at the tail and moving rc_snd_nxt up with snd_max.
    *
    * In recovery during SACK/ACK processing if a chunk has
    * been retransmitted and it is now acked, we decrement rc_holes_rxt.
    * When we retransmit from the scoreboard we use
    * rc_next and rc_snd_nxt/rc_send_end to help us
    * find what needs to be retran.
    *
    * To calculate pipe we simply take (snd_max - snd_una) + rc_holes_rxt
    * This gets us the effect of RFC6675 pipe, counting twice for
    * bytes retransmitted.
    */
   
   #define TT_RACK_FR_TMR  0x2000
   
   /*
    * Locking for the rack control block.
    * a) Locked by INP_WLOCK
    * b) Locked by the hpts-mutex
    *
    */
   #define RACK_GP_HIST 4  /* How much goodput history do we maintain? */
   
   #define RACK_NUM_FSB_DEBUG 16
   #ifdef _KERNEL
   struct rack_fast_send_blk {
           uint32_t left_to_send;
           uint16_t tcp_ip_hdr_len;
           uint8_t tcp_flags;
           uint8_t hoplimit;
           uint8_t *tcp_ip_hdr;
           uint32_t recwin;
           uint32_t off;
           struct tcphdr *th;
           struct udphdr *udp;
           struct mbuf *m;
           uint32_t o_m_len;
           uint32_t rfo_apply_push : 1,
                   hw_tls : 1,
                   unused : 30;
   };
   
   struct rack_control {
           /* Second cache line 0x40 from tcp_rack */
           struct rack_rb_tree_head rc_mtree; /* Tree of all segments Lock(a) */
           struct rack_head rc_tmap;       /* List in transmit order Lock(a) */
           struct rack_sendmap *rc_tlpsend;        /* Remembered place for
                                                    * tlp_sending Lock(a) */
           struct rack_sendmap *rc_resend; /* something we have been asked to
                                            * resend */
           struct rack_fast_send_blk fsb;  /* The fast-send block */
           uint32_t timer_slop;
           uint32_t input_pkt;
           uint32_t saved_input_pkt;
           uint32_t rc_hpts_flags;
           uint32_t rc_fixed_pacing_rate_ca;
           uint32_t rc_fixed_pacing_rate_rec;
           uint32_t rc_fixed_pacing_rate_ss;
           uint32_t cwnd_to_use;   /* The cwnd in use */
           uint32_t rc_timer_exp;  /* If a timer ticks of expiry */
           uint32_t rc_rack_min_rtt;       /* lowest RTT seen Lock(a) */
           uint32_t rc_rack_largest_cwnd;  /* Largest CWND we have seen Lock(a) */
   
           /* Third Cache line 0x80 */
           struct rack_head rc_free;       /* Allocation array */
           uint64_t last_hw_bw_req;
           uint64_t crte_prev_rate;
           uint64_t bw_rate_cap;
           uint32_t rc_reorder_ts; /* Last time we saw reordering Lock(a) */
   
           uint32_t rc_tlp_new_data;       /* we need to send new-data on a TLP
                                            * Lock(a) */
           uint32_t rc_prr_out;    /* bytes sent during recovery Lock(a) */
   
           uint32_t rc_prr_recovery_fs;    /* recovery fs point Lock(a) */
   
           uint32_t rc_prr_sndcnt; /* Prr sndcnt Lock(a) */
   
           uint32_t rc_sacked;     /* Tot sacked on scoreboard Lock(a) */
           uint32_t last_sent_tlp_seq;     /* Last tlp sequence that was retransmitted Lock(a) */
   
           uint32_t rc_prr_delivered;      /* during recovery prr var Lock(a) */
           uint16_t rc_tlp_cnt_out;        /* count of times we have sent a TLP without new data */
           uint16_t last_sent_tlp_len;     /* Number of bytes in the last sent tlp */
   
           uint32_t rc_loss_count; /* How many bytes have been retransmitted
                                    * Lock(a) */
           uint32_t rc_reorder_fade;       /* Socket option value Lock(a) */
   
           /* Forth cache line 0xc0  */
           /* Times */
   
           uint32_t rc_rack_tmit_time;     /* Rack transmit time Lock(a) */
           uint32_t rc_holes_rxt;  /* Tot retraned from scoreboard Lock(a) */
   
           uint32_t rc_num_maps_alloced;   /* Number of map blocks (sacks) we
                                            * have allocated */
           uint32_t rc_rcvtime;    /* When we last received data */
           uint32_t rc_num_split_allocs;   /* num split map entries allocated */
   
           uint32_t rc_last_output_to;
           uint32_t rc_went_idle_time;
   
           struct rack_sendmap *rc_sacklast;       /* sack remembered place
                                                    * Lock(a) */
   
           struct rack_sendmap *rc_first_appl;     /* Pointer to first app limited */
           struct rack_sendmap *rc_end_appl;       /* Pointer to last app limited */
           /* Cache line split 0x100 */
           struct sack_filter rack_sf;
           /* Cache line split 0x140 */
           /* Flags for various things */
           uint32_t rc_pace_max_segs;
           uint32_t rc_pace_min_segs;
           uint32_t rc_app_limited_cnt;
           uint16_t rack_per_of_gp_ss; /* 100 = 100%, so from 65536 = 655 x bw  */
           uint16_t rack_per_of_gp_ca; /* 100 = 100%, so from 65536 = 655 x bw  */
           uint16_t rack_per_of_gp_rec; /* 100 = 100%, so from 65536 = 655 x bw, 0=off */
           uint16_t rack_per_of_gp_probertt; /* 100 = 100%, so from 65536 = 655 x bw, 0=off */
           uint32_t rc_high_rwnd;
           uint32_t ack_count;
           uint32_t sack_count;
           uint32_t sack_noextra_move;
           uint32_t sack_moved_extra;
           struct rack_rtt_sample rack_rs;
           const struct tcp_hwrate_limit_table *crte;
           uint32_t rc_agg_early;
           uint32_t rc_agg_delayed;
           uint32_t rc_tlp_rxt_last_time;
           uint32_t rc_saved_cwnd;
           uint64_t rc_gp_output_ts; /* chg*/
           uint64_t rc_gp_cumack_ts; /* chg*/
           struct timeval act_rcv_time;
           struct timeval rc_last_time_decay;      /* SAD time decay happened here */
           uint64_t gp_bw;
           uint64_t init_rate;
   #ifdef NETFLIX_SHARED_CWND
           struct shared_cwnd *rc_scw;
   #endif
           uint64_t last_gp_comp_bw;
           uint64_t last_max_bw;   /* Our calculated max b/w last */
           struct time_filter_small rc_gp_min_rtt;
           struct def_opt_head opt_list;
           int32_t rc_rtt_diff;            /* Timely style rtt diff of our gp_srtt */
           uint32_t rc_gp_srtt;            /* Current GP srtt */
           uint32_t rc_prev_gp_srtt;       /* Previous RTT */
           uint32_t rc_entry_gp_rtt;       /* Entry to PRTT gp-rtt */
           uint32_t rc_loss_at_start;      /* At measurement window where was our lost value */
   
           uint32_t dsack_round_end;       /* In a round of seeing a DSACK */
           uint32_t current_round;         /* Starting at zero */
           uint32_t roundends;             /* acked value above which round ends */
           uint32_t num_dsack;             /* Count of dsack's seen  (1 per window)*/
           uint32_t forced_ack_ts;
           uint32_t last_collapse_point;   /* Last point peer collapsed too */
           uint32_t high_collapse_point;
           uint32_t rc_lower_rtt_us_cts;   /* Time our GP rtt was last lowered */
           uint32_t rc_time_probertt_entered;
           uint32_t rc_time_probertt_starts;
           uint32_t rc_lowest_us_rtt;
           uint32_t rc_highest_us_rtt;
           uint32_t rc_last_us_rtt;
           uint32_t rc_time_of_last_probertt;
           uint32_t rc_target_probertt_flight;
           uint32_t rc_probertt_sndmax_atexit;     /* Highest sent to in probe-rtt */
           uint32_t rc_cwnd_at_erec;
           uint32_t rc_ssthresh_at_erec;
           uint32_t dsack_byte_cnt;
           uint32_t retran_during_recovery;
           uint32_t rc_gp_lowrtt;                  /* Lowest rtt seen during GPUT measurement */
           uint32_t rc_gp_high_rwnd;               /* Highest rwnd seen during GPUT measurement */
           uint32_t rc_snd_max_at_rto;     /* For non-sack when the RTO occurred what was snd-max */
           uint32_t rc_out_at_rto;
           int32_t rc_scw_index;
           uint32_t rc_tlp_threshold;      /* Socket option value Lock(a) */
           uint32_t rc_last_timeout_snduna;
           uint32_t last_tlp_acked_start;
           uint32_t last_tlp_acked_end;
           uint32_t challenge_ack_ts;
           uint32_t challenge_ack_cnt;
           uint32_t rc_min_to;     /* Socket option value Lock(a) */
           uint32_t rc_pkt_delay;  /* Socket option value Lock(a) */
           uint32_t persist_lost_ends;
           struct newreno rc_saved_beta;   /*
                                            * For newreno cc:
                                            * rc_saved_cc are the values we have had
                                            * set by the user, if pacing is not happening
                                            * (i.e. its early and we have not turned on yet
                                            *  or it was turned off). The minute pacing
                                            * is turned on we pull out the values currently
                                            * being used by newreno and replace them with
                                            * these values, then save off the old values here,
                                            * we also set the flag (if ecn_beta is set) to make
                                            * new_reno do less of a backoff for ecn (think abe).
                                            */
           uint16_t rc_early_recovery_segs;        /* Socket option value Lock(a) */
           uint16_t rc_reorder_shift;      /* Socket option value Lock(a) */
           uint8_t dsack_persist;
           uint8_t rc_no_push_at_mrtt;     /* No push when we exceed max rtt */
           uint8_t num_measurements;       /* Number of measurements (up to 0xff, we freeze at 0xff)  */
           uint8_t req_measurements;       /* How many measurements are required? */
           uint8_t rc_tlp_cwnd_reduce;     /* Socket option value Lock(a) */
           uint8_t rc_prr_sendalot;/* Socket option value Lock(a) */
           uint8_t rc_rate_sample_method;
   };
   #endif
   
   #define RACK_TIMELY_CNT_BOOST 5 /* At 5th increase boost */
   #define RACK_MINRTT_FILTER_TIM 10 /* Seconds */
   
   #define RACK_HYSTART_OFF        0
   #define RACK_HYSTART_ON         1       /* hystart++ on */
   #define RACK_HYSTART_ON_W_SC    2       /* hystart++ on +Slam Cwnd */
   #define RACK_HYSTART_ON_W_SC_C  3       /* hystart++ on,
                                            * Conservative ssthresh and
                                            * +Slam cwnd
                                            */
   
   #ifdef _KERNEL
   
   struct tcp_rack {
           /* First cache line 0x00 */
           TAILQ_ENTRY(tcp_rack) r_hpts;   /* hptsi queue next Lock(b) */
           int32_t(*r_substate) (struct mbuf *, struct tcphdr *,
               struct socket *, struct tcpcb *, struct tcpopt *,
               int32_t, int32_t, uint32_t, int, int, uint8_t);     /* Lock(a) */
           struct tcpcb *rc_tp;    /* The tcpcb Lock(a) */
           struct inpcb *rc_inp;   /* The inpcb Lock(a) */
           uint8_t rc_free_cnt;    /* Number of free entries on the rc_free list
                                    * Lock(a) */
           uint8_t client_bufferlvl : 3, /* Expected range [0,5]: 0=unset, 1=low/empty */
                   rack_deferred_inited : 1,
                   /* ******************************************************************** */
                   /* Note for details of next two fields see rack_init_retransmit_rate()  */
                   /* ******************************************************************** */
                   full_size_rxt: 1,
                   shape_rxt_to_pacing_min : 1,
                   /* ******************************************************************** */
                   rc_ack_required: 1,
                   spare : 1;
           uint8_t no_prr_addback : 1,
                   gp_ready : 1,
                   defer_options: 1,
                   fast_rsm_hack: 1,
                   rc_ack_can_sendout_data: 1, /*
                                                * If set it will override pacing restrictions on not sending
                                                * data when the pacing timer is running. I.e. you set this
                                                * and an ACK will send data. Default is off and its only used
                                                * without pacing when we are doing 5G speed up for there
                                                * ack filtering.
                                                */
                   rc_pacing_cc_set: 1,         /*
                                                 * If we are pacing (pace_always=1) and we have reached the
                                                 * point where we start pacing (fixed or gp has reached its
                                                 * magic gp_ready state) this flag indicates we have set in
                                                 * values to effect CC's backoff's. If pacing is turned off
                                                 * then we must restore the values saved in rc_saved_beta,
                                                 * if its going to gp_ready we need to copy the values into
                                                 * the CC module and set our flags.
                                                 *
                                                 * Note this only happens if the cc name is newreno (CCALGONAME_NEWRENO).
                                                 */
   
                   rc_rack_tmr_std_based :1,
                   rc_rack_use_dsack: 1;
           uint8_t rc_dsack_round_seen: 1,
                   rc_last_tlp_acked_set: 1,
                   rc_last_tlp_past_cumack: 1,
                   rc_last_sent_tlp_seq_valid: 1,
                   rc_last_sent_tlp_past_cumack: 1,
                   probe_not_answered: 1,
                   avail_bytes : 2;
           uint32_t rc_rack_rtt;   /* RACK-RTT Lock(a) */
           uint16_t r_mbuf_queue : 1,      /* Do we do mbuf queue for non-paced */
                    rtt_limit_mul : 4,     /* muliply this by low rtt */
                    r_limit_scw : 1,
                    r_must_retran : 1,     /* For non-sack customers we hit an RTO and new data should be resends */
                    r_use_cmp_ack: 1,      /* Do we use compressed acks */
                    r_ent_rec_ns: 1,       /* We entered recovery and have not sent */
                    r_might_revert: 1,     /* Flag to find out if we might need to revert */
                    r_fast_output: 1,      /* Fast output is in progress we can skip the bulk of rack_output */
                    r_fsb_inited: 1,
                    r_rack_hw_rate_caps: 1,
                    r_up_only: 1,
                    r_via_fill_cw : 1,
                    r_fill_less_agg : 1;
   
           uint8_t rc_user_set_max_segs;   /* Socket option value Lock(a) */
           uint8_t rc_labc;                /* Appropriate Byte Counting Value */
           uint16_t forced_ack : 1,
                   rc_gp_incr : 1,
                   rc_gp_bwred : 1,
                   rc_gp_timely_inc_cnt : 3,
                   rc_gp_timely_dec_cnt : 3,
                   r_use_labc_for_rec: 1,
                   rc_highly_buffered: 1,          /* The path is highly buffered */
                   rc_dragged_bottom: 1,
                   rc_dack_mode : 1,               /* Mac O/S emulation of d-ack */
                   rc_dack_toggle : 1,             /* For Mac O/S emulation of d-ack */
                   rc_gp_filled : 1,
                   rc_is_spare : 1;
           uint8_t r_state;        /* Current rack state Lock(a) */
           uint8_t rc_tmr_stopped : 7,
                   t_timers_stopped : 1;
           uint8_t rc_enobuf : 7,  /* count of enobufs on connection provides */
                   rc_on_min_to : 1;
           uint8_t r_timer_override : 1,   /* hpts override Lock(a) */
                   r_is_v6 : 1,    /* V6 pcb Lock(a)  */
                   rc_in_persist : 1,
                   rc_tlp_in_progress : 1,
                   rc_always_pace : 1,     /* Socket option value Lock(a) */
                   rc_pace_to_cwnd : 1,
                   rc_pace_fill_if_rttin_range : 1,
                   rc_srtt_measure_made : 1;
           uint8_t app_limited_needs_set : 1,
                   use_fixed_rate : 1,
                   rc_has_collapsed : 1,
                   r_rep_attack : 1,
                   r_rep_reverse : 1,
                   rack_hdrw_pacing : 1,  /* We are doing Hardware pacing */
                   rack_hdw_pace_ena : 1, /* Is hardware pacing enabled? */
                   rack_attempt_hdwr_pace : 1; /* Did we attempt hdwr pacing (if allowed) */
           uint8_t rack_tlp_threshold_use : 3,     /* only 1, 2 and 3 used so far */
                   rack_rec_nonrxt_use_cr : 1,
                   rack_enable_scwnd : 1,
                   rack_attempted_scwnd : 1,
                   rack_no_prr : 1,
                   rack_scwnd_is_idle : 1;
           uint8_t rc_allow_data_af_clo: 1,
                   delayed_ack : 1,
                   set_pacing_done_a_iw : 1,
                   use_rack_rr : 1,
                   alloc_limit_reported : 1,
                   sack_attack_disable : 1,
                   do_detection : 1,
                   rc_force_max_seg : 1;
           uint8_t r_early : 1,
                   r_late : 1,
                   r_wanted_output: 1,
                   r_rr_config : 2,
                   r_persist_lt_bw_off : 1,
                   r_collapse_point_valid : 1,
                   rc_avail_bit : 2;
           uint16_t rc_init_win : 8,
                   rc_gp_rtt_set : 1,
                   rc_gp_dyn_mul : 1,
                   rc_gp_saw_rec : 1,
                   rc_gp_saw_ca : 1,
                   rc_gp_saw_ss : 1,
                   rc_gp_no_rec_chg : 1,
                   in_probe_rtt : 1,
                   measure_saw_probe_rtt : 1;
           /* Cache line 2 0x40 */
           struct rack_control r_ctl;
   }        __aligned(CACHE_LINE_SIZE);
   
   #endif
   #endif

Cache object: e6c7cf615c39ba8b4029f2ca6dc36db6