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-rw-r--r--src/vnet/tcp/tcp.c7
-rw-r--r--src/vnet/tcp/tcp.h4
-rw-r--r--src/vnet/tcp/tcp_cli.c9
-rw-r--r--src/vnet/tcp/tcp_inlines.h4
-rw-r--r--src/vnet/tcp/tcp_input.c43
-rw-r--r--src/vnet/tcp/tcp_types.h14
6 files changed, 38 insertions, 43 deletions
diff --git a/src/vnet/tcp/tcp.c b/src/vnet/tcp/tcp.c
index c30a69304bc..938a863238f 100644
--- a/src/vnet/tcp/tcp.c
+++ b/src/vnet/tcp/tcp.c
@@ -681,7 +681,7 @@ tcp_init_snd_vars (tcp_connection_t * tc)
tc->snd_una = tc->iss;
tc->snd_nxt = tc->iss + 1;
tc->snd_una_max = tc->snd_nxt;
- tc->srtt = 100; /* 100 ms */
+ tc->srtt = 0.1 * THZ; /* 100 ms */
if (!tcp_cfg.csum_offload)
tc->cfg_flags |= TCP_CFG_F_NO_CSUM_OFFLOAD;
@@ -1361,11 +1361,6 @@ tcp_main_enable (vlib_main_t * vm)
pool_init_fixed (tm->half_open_connections,
tcp_cfg.preallocated_half_open_connections);
- /* Initialize clocks per tick for TCP timestamp. Used to compute
- * monotonically increasing timestamps. */
- tm->tstamp_ticks_per_clock = vm->clib_time.seconds_per_clock
- / TCP_TSTAMP_RESOLUTION;
-
if (num_threads > 1)
{
clib_spinlock_init (&tm->half_open_lock);
diff --git a/src/vnet/tcp/tcp.h b/src/vnet/tcp/tcp.h
index 91783a6e025..bc6e353b60e 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -91,7 +91,7 @@ typedef struct tcp_worker_ctx_
/** convenience pointer to this thread's vlib main */
vlib_main_t *vm;
- /** worker time */
+ /** Time measured in @ref TCP_TSTAMP_TICK used for time stamps */
u32 time_now;
/* Max timers to be handled per dispatch loop */
@@ -209,8 +209,6 @@ typedef struct _tcp_main
/* Pool of listeners. */
tcp_connection_t *listener_pool;
- f64 tstamp_ticks_per_clock;
-
/** vlib buffer size */
u32 bytes_per_buffer;
diff --git a/src/vnet/tcp/tcp_cli.c b/src/vnet/tcp/tcp_cli.c
index b76b40474a6..6030440435d 100644
--- a/src/vnet/tcp/tcp_cli.c
+++ b/src/vnet/tcp/tcp_cli.c
@@ -205,10 +205,11 @@ format_tcp_vars (u8 * s, va_list * args)
tc->rcv_opts.tsecr, tc->tsecr_last_ack,
tcp_time_now () - tc->tsval_recent_age);
s = format (s, " snd_mss %u\n", tc->snd_mss);
- s = format (s, " rto %u rto_boff %u srtt %u us %.3f rttvar %u rtt_ts %.4f",
- tc->rto, tc->rto_boff, tc->srtt, tc->mrtt_us * 1000, tc->rttvar,
- tc->rtt_ts);
- s = format (s, " rtt_seq %u\n", tc->rtt_seq - tc->iss);
+ s = format (s, " rto %u rto_boff %u srtt %.1f us %.3f rttvar %.1f",
+ tc->rto / 1000, tc->rto_boff, tc->srtt / 1000.0,
+ tc->mrtt_us * 1e3, tc->rttvar / 1000.0);
+ s = format (s, " rtt_ts %.4f rtt_seq %u\n", tc->rtt_ts,
+ tc->rtt_seq - tc->iss);
s = format (s, " next_node %u opaque 0x%x fib_index %u\n",
tc->next_node_index, tc->next_node_opaque, tc->c_fib_index);
s = format (s, " cong: %U", format_tcp_congestion, tc);
diff --git a/src/vnet/tcp/tcp_inlines.h b/src/vnet/tcp/tcp_inlines.h
index c4b155aa499..cb00ca4a97b 100644
--- a/src/vnet/tcp/tcp_inlines.h
+++ b/src/vnet/tcp/tcp_inlines.h
@@ -218,9 +218,7 @@ tcp_time_now_us (u32 thread_index)
always_inline u32
tcp_set_time_now (tcp_worker_ctx_t * wrk)
{
- tcp_main_t *tm = &tcp_main;
- wrk->time_now = (u64) (clib_cpu_time_now () * tm->tstamp_ticks_per_clock);
- return wrk->time_now;
+ return wrk->time_now = (u64) (vlib_time_now (wrk->vm) * TCP_TSTP_HZ);
}
always_inline tcp_connection_t *
diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index 519219e2c74..5fa7bf23c72 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -424,31 +424,26 @@ acceptable:
/**
* Compute smoothed RTT as per VJ's '88 SIGCOMM and RFC6298
*
- * Note that although the original article, srtt and rttvar are scaled
+ * Note that although in the original article srtt and rttvar are scaled
* to minimize round-off errors, here we don't. Instead, we rely on
* better precision time measurements.
+ *
+ * A known limitation of the algorithm is that a drop in rtt results in a
+ * rttvar increase and bigger RTO.
+ *
+ * mrtt must be provided in @ref TCP_TICK multiples, i.e., in us. Note that
+ * timestamps are measured as ms ticks so they must be converted before
+ * calling this function.
*/
static void
tcp_estimate_rtt (tcp_connection_t * tc, u32 mrtt)
{
int err, diff;
- if (tc->srtt != 0)
- {
- err = mrtt - tc->srtt;
-
- /* XXX Drop in RTT results in RTTVAR increase and bigger RTO.
- * The increase should be bound */
- tc->srtt = clib_max ((int) tc->srtt + (err >> 3), 1);
- diff = (clib_abs (err) - (int) tc->rttvar) >> 2;
- tc->rttvar = clib_max ((int) tc->rttvar + diff, 1);
- }
- else
- {
- /* First measurement. */
- tc->srtt = mrtt;
- tc->rttvar = mrtt >> 1;
- }
+ err = mrtt - tc->srtt;
+ tc->srtt = clib_max ((int) tc->srtt + (err >> 3), 1);
+ diff = (clib_abs (err) - (int) tc->rttvar) >> 2;
+ tc->rttvar = clib_max ((int) tc->rttvar + diff, 1);
}
static inline void
@@ -506,8 +501,8 @@ tcp_update_rtt (tcp_connection_t * tc, tcp_rate_sample_t * rs, u32 ack)
* seq_lt (tc->snd_una, ack). This is a condition for calling update_rtt */
else if (tcp_opts_tstamp (&tc->rcv_opts) && tc->rcv_opts.tsecr)
{
- u32 now = tcp_tstamp (tc);
- mrtt = clib_max (now - tc->rcv_opts.tsecr, 1);
+ mrtt = clib_max (tcp_tstamp (tc) - tc->rcv_opts.tsecr, 1);
+ mrtt *= TCP_TSTP_TO_HZ;
}
estimate_rtt:
@@ -543,8 +538,8 @@ tcp_estimate_initial_rtt (tcp_connection_t * tc)
}
else
{
- mrtt = tcp_time_now_w_thread (thread_index) - tc->rcv_opts.tsecr;
- mrtt = clib_max (mrtt, 1);
+ mrtt = tcp_tstamp (tc) - tc->rcv_opts.tsecr;
+ mrtt = clib_max (mrtt, 1) * TCP_TSTP_TO_HZ;
/* Due to retransmits we don't know the initial mrtt */
if (tc->rto_boff && mrtt > 1 * THZ)
mrtt = 1 * THZ;
@@ -552,7 +547,11 @@ tcp_estimate_initial_rtt (tcp_connection_t * tc)
}
if (mrtt > 0 && mrtt < TCP_RTT_MAX)
- tcp_estimate_rtt (tc, mrtt);
+ {
+ /* First measurement as per RFC 6298 */
+ tc->srtt = mrtt;
+ tc->rttvar = mrtt >> 1;
+ }
tcp_update_rto (tc);
}
diff --git a/src/vnet/tcp/tcp_types.h b/src/vnet/tcp/tcp_types.h
index 3cf4e9e33ef..d7bcac5e3bc 100644
--- a/src/vnet/tcp/tcp_types.h
+++ b/src/vnet/tcp/tcp_types.h
@@ -22,10 +22,14 @@
#include <vnet/session/transport.h>
#include <vppinfra/tw_timer_16t_2w_512sl.h>
-#define TCP_TICK 0.001 /**< TCP tick period (s) */
-#define THZ (u32) (1/TCP_TICK) /**< TCP tick frequency */
-#define TCP_TSTAMP_RESOLUTION TCP_TICK /**< Time stamp resolution */
-#define TCP_PAWS_IDLE 24 * 24 * 60 * 60 * THZ /**< 24 days */
+#define TCP_TICK 0.000001 /**< TCP tick period (s) */
+#define THZ (u32) (1/TCP_TICK) /**< TCP tick frequency */
+
+#define TCP_TSTP_TICK 0.001 /**< Timestamp tick (s) */
+#define TCP_TSTP_HZ (u32) (1/TCP_TSTP_TICK) /**< Timestamp freq */
+#define TCP_PAWS_IDLE (24 * 86400 * TCP_TSTP_HZ)/**< 24 days */
+#define TCP_TSTP_TO_HZ (u32) (TCP_TSTP_TICK * THZ)
+
#define TCP_FIB_RECHECK_PERIOD 1 * THZ /**< Recheck every 1s */
#define TCP_MAX_OPTION_SPACE 40
#define TCP_CC_DATA_SZ 24
@@ -355,7 +359,7 @@ typedef struct _tcp_connection
/* RTT and RTO */
u32 rto; /**< Retransmission timeout */
u32 rto_boff; /**< Index for RTO backoff */
- u32 srtt; /**< Smoothed RTT */
+ u32 srtt; /**< Smoothed RTT measured in @ref TCP_TICK */
u32 rttvar; /**< Smoothed mean RTT difference. Approximates variance */
u32 rtt_seq; /**< Sequence number for tracked ACK */
f64 rtt_ts; /**< Timestamp for tracked ACK */