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authorFlorin Coras <fcoras@cisco.com>2020-07-31 12:32:40 -0700
committerFlorin Coras <florin.coras@gmail.com>2020-08-03 15:36:32 +0000
commiteedc74b804a955de39e013f14c97f2abb4770157 (patch)
tree6c9e640858a6f4b548c67ae8d2f97e9d69fdab47 /src/vnet/tcp/tcp.c
parentf3ae9e32664ccc3ce0980fcafee9453a3c0cef9b (diff)
tcp: improve timestamp rtt accuracy
- switch to using vlib_time as reference for timestamps - use us precision ticks for tcp but keep using ms precision for timestamps. As a result, srtt, rttvar and rto are now measured in us instead of ms. MRTT samples from timestamps are converted from ms to us (not accurate under ms) while high precision samples are used with us precision, i.e., they're no longer converted to ms precision samples. Type: improvement Change-Id: Ibda559575d9b4fdc85b0985264f7c865ff367e34 Signed-off-by: Florin Coras <fcoras@cisco.com>
Diffstat (limited to 'src/vnet/tcp/tcp.c')
-rw-r--r--src/vnet/tcp/tcp.c7
1 files changed, 1 insertions, 6 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);