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Set slow start threshold more accurately on loss to be flightsize/2 instead of

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cwnd/2 as recommended by RFC5681. (spotted by mmacy at nextbsd dot org)

Restore pre-r307901 behavior of aligning ssthresh/cwnd on mss boundary. (spotted
by slawa at zxy dot spb dot ru)

Tested by:	    dim, Slawa <slawa at zxy dot spb dot ru>
MFC after:	    1 month
X-MFC with:	    r307901
Sponsored by:	    Limelight Networks
Differential Revision:	https://reviews.freebsd.org/D8349
This commit is contained in:
Hiren Panchasara 2016-11-01 21:08:37 +00:00
parent 8e269d996a
commit e04310d59b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=308180
6 changed files with 31 additions and 19 deletions
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4
sys/netinet/cc/cc_cdg.c
View File

@ -474,7 +474,9 @@ cdg_cong_signal(struct cc_var *ccv, uint32_t signal_type)
ENTER_RECOVERY(CCV(ccv, t_flags));
break;
case CC_RTO:
CCV(ccv, snd_ssthresh) = max(2*mss, cwin/2);
CCV(ccv, snd_ssthresh) =
max((CCV(ccv, snd_max) - CCV(ccv, snd_una)) / 2 / mss, 2)
* mss;
CCV(ccv, snd_cwnd) = mss;
break;
default:

6
sys/netinet/cc/cc_chd.c
View File

@ -330,13 +330,11 @@ chd_cong_signal(struct cc_var *ccv, uint32_t signal_type)
struct ertt *e_t;
struct chd *chd_data;
int qdly;
uint32_t cwin;
u_int mss;
e_t = khelp_get_osd(CCV(ccv, osd), ertt_id);
chd_data = ccv->cc_data;
qdly = imax(e_t->rtt, chd_data->maxrtt_in_rtt) - e_t->minrtt;
cwin = CCV(ccv, snd_cwnd);
mss = CCV(ccv, t_maxseg);
switch(signal_type) {
@ -378,7 +376,9 @@ chd_cong_signal(struct cc_var *ccv, uint32_t signal_type)
ENTER_FASTRECOVERY(CCV(ccv, t_flags));
break;
case CC_RTO:
CCV(ccv, snd_ssthresh) = max(2*mss, cwin/2);
CCV(ccv, snd_ssthresh) =
max((CCV(ccv, snd_max) - CCV(ccv, snd_una)) / 2 / mss, 2)
* mss;
CCV(ccv, snd_cwnd) = mss;
break;

16
sys/netinet/cc/cc_dctcp.c
View File

@ -230,19 +230,21 @@ static void
dctcp_cong_signal(struct cc_var *ccv, uint32_t type)
{
struct dctcp *dctcp_data;
uint32_t cwin;
uint32_t cwin, ssthresh_on_loss;
u_int mss;
dctcp_data = ccv->cc_data;
cwin = CCV(ccv, snd_cwnd);
mss = CCV(ccv, t_maxseg);
ssthresh_on_loss =
max((CCV(ccv, snd_max) - CCV(ccv, snd_una)) / 2 / mss, 2)
* mss;
switch (type) {
case CC_NDUPACK:
if (!IN_FASTRECOVERY(CCV(ccv, t_flags))) {
if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
CCV(ccv, snd_ssthresh) = mss *
max(cwin / 2 / mss, 2);
CCV(ccv, snd_ssthresh) = ssthresh_on_loss;
dctcp_data->num_cong_events++;
} else {
/* cwnd has already updated as congestion
@ -250,8 +252,7 @@ dctcp_cong_signal(struct cc_var *ccv, uint32_t type)
* snd_cwnd_prev and recalculate snd_ssthresh
*/
cwin = CCV(ccv, snd_cwnd_prev);
CCV(ccv, snd_ssthresh) =
max(cwin / 2 / mss, 2) * mss;
CCV(ccv, snd_ssthresh) = ssthresh_on_loss;
}
ENTER_RECOVERY(CCV(ccv, t_flags));
}
@ -265,8 +266,7 @@ dctcp_cong_signal(struct cc_var *ccv, uint32_t type)
if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
if (V_dctcp_slowstart &&
dctcp_data->num_cong_events++ == 0) {
CCV(ccv, snd_ssthresh) =
mss * max(cwin / 2 / mss, 2);
CCV(ccv, snd_ssthresh) = ssthresh_on_loss;
dctcp_data->alpha = MAX_ALPHA_VALUE;
dctcp_data->bytes_ecn = 0;
dctcp_data->bytes_total = 0;
@ -285,7 +285,7 @@ dctcp_cong_signal(struct cc_var *ccv, uint32_t type)
dctcp_update_alpha(ccv);
dctcp_data->save_sndnxt += CCV(ccv, t_maxseg);
dctcp_data->num_cong_events++;
CCV(ccv, snd_ssthresh) = max(2 * mss, cwin / 2);
CCV(ccv, snd_ssthresh) = ssthresh_on_loss;
CCV(ccv, snd_cwnd) = mss;
}
break;

8
sys/netinet/cc/cc_htcp.c
View File

@ -325,7 +325,9 @@ htcp_cong_signal(struct cc_var *ccv, uint32_t type)
*/
if (CCV(ccv, t_rxtshift) >= 2)
htcp_data->t_last_cong = ticks;
CCV(ccv, snd_ssthresh) = max(2 * mss, cwin / 2);
CCV(ccv, snd_ssthresh) =
max((CCV(ccv, snd_max) - CCV(ccv, snd_una)) / 2 / mss, 2)
* mss;
CCV(ccv, snd_cwnd) = mss;
break;
}
@ -518,6 +520,10 @@ htcp_ssthresh_update(struct cc_var *ccv)
CCV(ccv, snd_ssthresh) = ((u_long)CCV(ccv, snd_cwnd) *
htcp_data->beta) >> HTCP_SHIFT;
}
/* Align ssthresh to MSS boundary */
CCV(ccv, snd_ssthresh) = (CCV(ccv, snd_ssthresh) / CCV(ccv, t_maxseg))
* CCV(ccv, t_maxseg);
}

13
sys/netinet/cc/cc_newreno.c
View File

@ -182,23 +182,26 @@ newreno_after_idle(struct cc_var *ccv)
static void
newreno_cong_signal(struct cc_var *ccv, uint32_t type)
{
uint32_t cwin;
uint32_t cwin, ssthresh_on_loss;
u_int mss;
cwin = CCV(ccv, snd_cwnd);
mss = CCV(ccv, t_maxseg);
ssthresh_on_loss =
max((CCV(ccv, snd_max) - CCV(ccv, snd_una)) / 2 / mss, 2)
* mss;
/* Catch algos which mistakenly leak private signal types. */
KASSERT((type & CC_SIGPRIVMASK) == 0,
("%s: congestion signal type 0x%08x is private\n", __func__, type));
cwin = max(2*mss, cwin/2);
cwin = max(cwin / 2 / mss, 2) * mss;
switch (type) {
case CC_NDUPACK:
if (!IN_FASTRECOVERY(CCV(ccv, t_flags))) {
if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
CCV(ccv, snd_ssthresh) = cwin;
CCV(ccv, snd_ssthresh) = ssthresh_on_loss;
CCV(ccv, snd_cwnd) = cwin;
}
ENTER_RECOVERY(CCV(ccv, t_flags));
@ -206,13 +209,13 @@ newreno_cong_signal(struct cc_var *ccv, uint32_t type)
break;
case CC_ECN:
if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
CCV(ccv, snd_ssthresh) = cwin;
CCV(ccv, snd_ssthresh) = ssthresh_on_loss;
CCV(ccv, snd_cwnd) = cwin;
ENTER_CONGRECOVERY(CCV(ccv, t_flags));
}
break;
case CC_RTO:
CCV(ccv, snd_ssthresh) = cwin;
CCV(ccv, snd_ssthresh) = ssthresh_on_loss;
CCV(ccv, snd_cwnd) = mss;
break;
}

3
sys/netinet/tcp_input.c
View File

@ -444,7 +444,8 @@ cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type)
* ssthresh = max (FlightSize / 2, 2*SMSS) eq (4)
*/
tp->snd_ssthresh =
max((tp->snd_max - tp->snd_una) / 2, 2 * maxseg);
max((tp->snd_max - tp->snd_una) / 2 / maxseg, 2)
* maxseg;
tp->snd_cwnd = maxseg;
}
break;