6e6439b238
HPTS timing begins to go off when we reach the threshold of connections (1200 by default) where we have any returning syscall or LRO stop finding the oldest hpts thread that has not run but instead using the CPU it is on. This ends up causing quite a lot of times where hpts threads may not run for extended periods of time. On top of all that which causes heartburn if you are pacing in tcp, you also have the fact that where AMD's podded L3 cache may have sets of 8 CPU's that share a L3, hpts is unaware of this and thus on amd you can generate a lot of cache misses. So to fix this we will get rid of the CPU mode, and always use oldest. But also make HPTS aware of the CPU topology and keep the "oldest" to be within the same L3 cache. This also works nicely for NUMA as well couple with Drew's earlier NUMA changes. Reviewed by: glebius, gallatin, tuexen Sponsored by: Netflix Inc. Differential Revision: https://reviews.freebsd.org/D34916
214 lines
7.5 KiB
C
214 lines
7.5 KiB
C
/*-
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* Copyright (c) 2016-2018 Netflix, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef __tcp_hpts_h__
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#define __tcp_hpts_h__
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/* Number of useconds in a hpts tick */
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#define HPTS_TICKS_PER_SLOT 10
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#define HPTS_MS_TO_SLOTS(x) ((x * 100) + 1)
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#define HPTS_USEC_TO_SLOTS(x) ((x+9) /10)
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#define HPTS_USEC_IN_SEC 1000000
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#define HPTS_MSEC_IN_SEC 1000
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#define HPTS_USEC_IN_MSEC 1000
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struct hpts_diag {
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uint32_t p_hpts_active; /* bbr->flex7 x */
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uint32_t p_nxt_slot; /* bbr->flex1 x */
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uint32_t p_cur_slot; /* bbr->flex2 x */
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uint32_t p_prev_slot; /* bbr->delivered */
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uint32_t p_runningslot; /* bbr->inflight */
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uint32_t slot_req; /* bbr->flex3 x */
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uint32_t inp_hptsslot; /* bbr->flex4 x */
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uint32_t slot_remaining; /* bbr->flex5 x */
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uint32_t have_slept; /* bbr->epoch x */
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uint32_t hpts_sleep_time; /* bbr->applimited x */
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uint32_t yet_to_sleep; /* bbr->lt_epoch x */
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uint32_t need_new_to; /* bbr->flex6 x */
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uint32_t wheel_slot; /* bbr->bw_inuse x */
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uint32_t maxslots; /* bbr->delRate x */
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uint32_t wheel_cts; /* bbr->rttProp x */
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int32_t co_ret; /* bbr->pkts_out x */
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uint32_t p_curtick; /* upper bbr->cur_del_rate */
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uint32_t p_lasttick; /* lower bbr->cur_del_rate */
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uint8_t p_on_min_sleep; /* bbr->flex8 x */
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};
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/* Magic flags to tell whats cooking on the pacing wheel */
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#define PACE_TMR_DELACK 0x01 /* Delayed ack timer running */
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#define PACE_TMR_RACK 0x02 /* RACK timer running */
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#define PACE_TMR_TLP 0x04 /* TLP timer running */
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#define PACE_TMR_RXT 0x08 /* Retransmit timer running */
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#define PACE_TMR_PERSIT 0x10 /* Persists timer running */
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#define PACE_TMR_KEEP 0x20 /* Keep alive timer running */
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#define PACE_PKT_OUTPUT 0x40 /* Output Packets being paced */
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#define PACE_TMR_MASK (PACE_TMR_KEEP|PACE_TMR_PERSIT|PACE_TMR_RXT|PACE_TMR_TLP|PACE_TMR_RACK|PACE_TMR_DELACK)
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#define DEFAULT_CONNECTION_THESHOLD 100
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/*
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* When using the hpts, a TCP stack must make sure
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* that once a INP_DROPPED flag is applied to a INP
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* that it does not expect tcp_output() to ever be
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* called by the hpts. The hpts will *not* call
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* any output (or input) functions on a TCB that
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* is in the DROPPED state.
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*
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* This implies final ACK's and RST's that might
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* be sent when a TCB is still around must be
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* sent from a routine like tcp_respond().
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*/
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#define LOWEST_SLEEP_ALLOWED 50
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#define DEFAULT_MIN_SLEEP 250 /* How many usec's is default for hpts sleep
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* this determines min granularity of the
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* hpts. If 1, granularity is 10useconds at
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* the cost of more CPU (context switching).
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* Note do not set this to 0.
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*/
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#define DYNAMIC_MIN_SLEEP DEFAULT_MIN_SLEEP
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#define DYNAMIC_MAX_SLEEP 5000 /* 5ms */
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/* Thresholds for raising/lowering sleep */
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#define TICKS_INDICATE_MORE_SLEEP 100 /* This would be 1ms */
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#define TICKS_INDICATE_LESS_SLEEP 1000 /* This would indicate 10ms */
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/**
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*
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* Dynamic adjustment of sleeping times is done in "new" mode
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* where we are depending on syscall returns and lro returns
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* to push hpts forward mainly and the timer is only a backstop.
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*
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* When we are in the "new" mode i.e. conn_cnt > conn_cnt_thresh
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* then we do a dynamic adjustment on the time we sleep.
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* Our threshold is if the lateness of the first client served (in ticks) is
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* greater than or equal too ticks_indicate_more_sleep (10ms
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* or 10000 ticks). If we were that late, the actual sleep time
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* is adjusted down by 50%. If the ticks_ran is less than
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* ticks_indicate_more_sleep (100 ticks or 1000usecs).
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*
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*/
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#ifdef _KERNEL
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void tcp_hpts_remove(struct inpcb *);
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bool tcp_in_hpts(struct inpcb *);
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/*
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* To insert a TCB on the hpts you *must* be holding the
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* INP_WLOCK(). The hpts insert code will then acqurire
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* the hpts's lock and insert the TCB on the requested
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* slot possibly waking up the hpts if you are requesting
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* a time earlier than what the hpts is sleeping to (if
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* the hpts is sleeping). You may check the inp->inp_in_hpts
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* flag without the hpts lock. The hpts is the only one
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* that will clear this flag holding only the hpts lock. This
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* means that in your tcp_output() routine when you test for
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* it to be 1 (so you wont call output) it may be transitioning
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* to 0 (by the hpts). That will be fine since that will just
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* mean an extra call to tcp_output that most likely will find
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* the call you executed (when the mis-match occured) will have
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* put the TCB back on the hpts and it will return. If your
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* call did not add it back to the hpts then you will either
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* over-send or the cwnd will block you from sending more.
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*
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* Note you should also be holding the INP_WLOCK() when you
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* call the remove from the hpts as well. Thoug usually
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* you are either doing this from a timer, where you need
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* that INP_WLOCK() or from destroying your TCB where again
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* you should already have the INP_WLOCK().
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*/
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uint32_t tcp_hpts_insert_diag(struct inpcb *inp, uint32_t slot, int32_t line,
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struct hpts_diag *diag);
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#define tcp_hpts_insert(inp, slot) \
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tcp_hpts_insert_diag((inp), (slot), __LINE__, NULL)
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void __tcp_set_hpts(struct inpcb *inp, int32_t line);
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#define tcp_set_hpts(a) __tcp_set_hpts(a, __LINE__)
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void tcp_set_inp_to_drop(struct inpcb *inp, uint16_t reason);
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void tcp_run_hpts(void);
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uint16_t hpts_random_cpu(struct inpcb *inp);
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extern int32_t tcp_min_hptsi_time;
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#endif /* _KERNEL */
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/*
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* The following functions should also be available
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* to userspace as well.
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*/
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static __inline uint32_t
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tcp_tv_to_hptstick(const struct timeval *sv)
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{
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return ((sv->tv_sec * 100000) + (sv->tv_usec / HPTS_TICKS_PER_SLOT));
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}
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static __inline uint32_t
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tcp_tv_to_usectick(const struct timeval *sv)
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{
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return ((uint32_t) ((sv->tv_sec * HPTS_USEC_IN_SEC) + sv->tv_usec));
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}
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static __inline uint32_t
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tcp_tv_to_mssectick(const struct timeval *sv)
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{
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return ((uint32_t) ((sv->tv_sec * HPTS_MSEC_IN_SEC) + (sv->tv_usec/HPTS_USEC_IN_MSEC)));
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}
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static __inline uint64_t
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tcp_tv_to_lusectick(const struct timeval *sv)
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{
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return ((uint64_t)((sv->tv_sec * HPTS_USEC_IN_SEC) + sv->tv_usec));
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}
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#ifdef _KERNEL
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static __inline uint32_t
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tcp_gethptstick(struct timeval *sv)
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{
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struct timeval tv;
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if (sv == NULL)
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sv = &tv;
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microuptime(sv);
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return (tcp_tv_to_hptstick(sv));
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}
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static __inline uint32_t
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tcp_get_usecs(struct timeval *tv)
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{
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struct timeval tvd;
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if (tv == NULL)
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tv = &tvd;
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microuptime(tv);
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return (tcp_tv_to_usectick(tv));
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}
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#endif /* _KERNEL */
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#endif /* __tcp_hpts_h__ */
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