Differential D14141 Diff 40760 head/sys/netinet/cc/cc_cubic.c

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head/sys/netinet/cc/cc_cubic.c

Show First 20 Lines • Show All 82 Lines • ▼ Show 20 Lines	struct cubic {
/* Cubic K in fixed point form with CUBIC_SHIFT worth of precision. */		/* Cubic K in fixed point form with CUBIC_SHIFT worth of precision. */
int64_t K;		int64_t K;
/* Sum of RTT samples across an epoch in ticks. */		/* Sum of RTT samples across an epoch in ticks. */
int64_t sum_rtt_ticks;		int64_t sum_rtt_ticks;
/* cwnd at the most recent congestion event. */		/* cwnd at the most recent congestion event. */
unsigned long max_cwnd;		unsigned long max_cwnd;
/* cwnd at the previous congestion event. */		/* cwnd at the previous congestion event. */
unsigned long prev_max_cwnd;		unsigned long prev_max_cwnd;
		/* Cached value for t_maxseg when K was computed */
		uint32_t k_maxseg;
/* Number of congestion events. */		/* Number of congestion events. */
uint32_t num_cong_events;		uint32_t num_cong_events;
/* Minimum observed rtt in ticks. */		/* Minimum observed rtt in ticks. */
int min_rtt_ticks;		int min_rtt_ticks;
/* Mean observed rtt between congestion epochs. */		/* Mean observed rtt between congestion epochs. */
int mean_rtt_ticks;		int mean_rtt_ticks;
/* ACKs since last congestion event. */		/* ACKs since last congestion event. */
int epoch_ack_count;		int epoch_ack_count;
Show All 20 Lines
{		{
struct cubic *cubic_data;		struct cubic *cubic_data;
unsigned long w_tf, w_cubic_next;		unsigned long w_tf, w_cubic_next;
int ticks_since_cong;		int ticks_since_cong;

cubic_data = ccv->cc_data;		cubic_data = ccv->cc_data;
cubic_record_rtt(ccv);		cubic_record_rtt(ccv);

		if (ccv->flags & CCF_MAX_CWND)
		return;

/*		/*
* Regular ACK and we're not in cong/fast recovery and we're cwnd		* Regular ACK and we're not in cong/fast recovery and we're cwnd
* limited and we're either not doing ABC or are slow starting or are		* limited and we're either not doing ABC or are slow starting or are
* doing ABC and we've sent a cwnd's worth of bytes.		* doing ABC and we've sent a cwnd's worth of bytes.
*/		*/
if (type == CC_ACK && !IN_RECOVERY(CCV(ccv, t_flags)) &&		if (type == CC_ACK && !IN_RECOVERY(CCV(ccv, t_flags)) &&
(ccv->flags & CCF_CWND_LIMITED) && (!V_tcp_do_rfc3465 \|\|		(ccv->flags & CCF_CWND_LIMITED) && (!V_tcp_do_rfc3465 \|\|
CCV(ccv, snd_cwnd) <= CCV(ccv, snd_ssthresh) \|\|		CCV(ccv, snd_cwnd) <= CCV(ccv, snd_ssthresh) \|\|
Show All 11 Lines	else {
* causes w_tf to grow much faster than it should if the		* causes w_tf to grow much faster than it should if the
* RTT is dominated by network buffering rather than		* RTT is dominated by network buffering rather than
* propagation delay.		* propagation delay.
*/		*/
w_tf = tf_cwnd(ticks_since_cong,		w_tf = tf_cwnd(ticks_since_cong,
cubic_data->mean_rtt_ticks, cubic_data->max_cwnd,		cubic_data->mean_rtt_ticks, cubic_data->max_cwnd,
CCV(ccv, t_maxseg));		CCV(ccv, t_maxseg));

		if (ccv->flags & CCF_CHG_MAX_CWND \|\| cubic_data->k_maxseg != CCV(ccv, t_maxseg)) {
		cubic_data->K = cubic_k(cubic_data->max_cwnd / CCV(ccv, t_maxseg));
		cubic_data->k_maxseg = CCV(ccv, t_maxseg);
		ccv->flags &= ~(CCF_MAX_CWND\|CCF_CHG_MAX_CWND);
		}

w_cubic_next = cubic_cwnd(ticks_since_cong +		w_cubic_next = cubic_cwnd(ticks_since_cong +
cubic_data->mean_rtt_ticks, cubic_data->max_cwnd,		cubic_data->mean_rtt_ticks, cubic_data->max_cwnd,
CCV(ccv, t_maxseg), cubic_data->K);		CCV(ccv, t_maxseg), cubic_data->K);

ccv->flags &= ~CCF_ABC_SENTAWND;		ccv->flags &= ~CCF_ABC_SENTAWND;

if (w_cubic_next < w_tf)		if (w_cubic_next < w_tf)
/*		/*
* TCP-friendly region, follow tf		* TCP-friendly region, follow tf
* cwnd growth.		* cwnd growth.
*/		*/
CCV(ccv, snd_cwnd) = w_tf;		CCV(ccv, snd_cwnd) = ulmin(w_tf, TCP_MAXWIN << CCV(ccv, snd_scale));

else if (CCV(ccv, snd_cwnd) < w_cubic_next) {		else if (CCV(ccv, snd_cwnd) < w_cubic_next) {
/*		/*
* Concave or convex region, follow CUBIC		* Concave or convex region, follow CUBIC
* cwnd growth.		* cwnd growth.
*/		*/
		if (w_cubic_next >= TCP_MAXWIN << CCV(ccv, snd_scale)) {
		w_cubic_next = TCP_MAXWIN << CCV(ccv, snd_scale);
		ccv->flags \|= CCF_MAX_CWND;
		}
		w_cubic_next = ulmin(w_cubic_next, TCP_MAXWIN << CCV(ccv, snd_scale));
if (V_tcp_do_rfc3465)		if (V_tcp_do_rfc3465)
CCV(ccv, snd_cwnd) = w_cubic_next;		CCV(ccv, snd_cwnd) = w_cubic_next;
else		else
CCV(ccv, snd_cwnd) += ((w_cubic_next -		CCV(ccv, snd_cwnd) += ((w_cubic_next -
CCV(ccv, snd_cwnd)) *		CCV(ccv, snd_cwnd)) *
CCV(ccv, t_maxseg)) /		CCV(ccv, t_maxseg)) /
CCV(ccv, snd_cwnd);		CCV(ccv, snd_cwnd);
}		}

/*		/*
* If we're not in slow start and we're probing for a		* If we're not in slow start and we're probing for a
* new cwnd limit at the start of a connection		* new cwnd limit at the start of a connection
* (happens when hostcache has a relevant entry),		* (happens when hostcache has a relevant entry),
* keep updating our current estimate of the		* keep updating our current estimate of the
* max_cwnd.		* max_cwnd.
*/		*/
if (cubic_data->num_cong_events == 0 &&		if (cubic_data->num_cong_events == 0 &&
cubic_data->max_cwnd < CCV(ccv, snd_cwnd))		cubic_data->max_cwnd < CCV(ccv, snd_cwnd)) {
cubic_data->max_cwnd = CCV(ccv, snd_cwnd);		cubic_data->max_cwnd = CCV(ccv, snd_cwnd);
		ccv->flags \|= CCF_CHG_MAX_CWND;
}		}
}		}
}		}
		}

static void		static void
cubic_cb_destroy(struct cc_var *ccv)		cubic_cb_destroy(struct cc_var *ccv)
{		{

if (ccv->cc_data != NULL)		if (ccv->cc_data != NULL)
free(ccv->cc_data, M_CUBIC);		free(ccv->cc_data, M_CUBIC);
}		}
Show All 31 Lines	cubic_cong_signal(struct cc_var *ccv, uint32_t type)
switch (type) {		switch (type) {
case CC_NDUPACK:		case CC_NDUPACK:
if (!IN_FASTRECOVERY(CCV(ccv, t_flags))) {		if (!IN_FASTRECOVERY(CCV(ccv, t_flags))) {
if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {		if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
cubic_ssthresh_update(ccv);		cubic_ssthresh_update(ccv);
cubic_data->num_cong_events++;		cubic_data->num_cong_events++;
cubic_data->prev_max_cwnd = cubic_data->max_cwnd;		cubic_data->prev_max_cwnd = cubic_data->max_cwnd;
cubic_data->max_cwnd = CCV(ccv, snd_cwnd);		cubic_data->max_cwnd = CCV(ccv, snd_cwnd);
		ccv->flags \|= CCF_CHG_MAX_CWND;
}		}
ENTER_RECOVERY(CCV(ccv, t_flags));		ENTER_RECOVERY(CCV(ccv, t_flags));
}		}
break;		break;

case CC_ECN:		case CC_ECN:
if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {		if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
cubic_ssthresh_update(ccv);		cubic_ssthresh_update(ccv);
cubic_data->num_cong_events++;		cubic_data->num_cong_events++;
cubic_data->prev_max_cwnd = cubic_data->max_cwnd;		cubic_data->prev_max_cwnd = cubic_data->max_cwnd;
cubic_data->max_cwnd = CCV(ccv, snd_cwnd);		cubic_data->max_cwnd = CCV(ccv, snd_cwnd);
cubic_data->t_last_cong = ticks;		cubic_data->t_last_cong = ticks;
		ccv->flags \|= CCF_CHG_MAX_CWND;
		ccv->flags &= ~CCF_MAX_CWND;
CCV(ccv, snd_cwnd) = CCV(ccv, snd_ssthresh);		CCV(ccv, snd_cwnd) = CCV(ccv, snd_ssthresh);
ENTER_CONGRECOVERY(CCV(ccv, t_flags));		ENTER_CONGRECOVERY(CCV(ccv, t_flags));
}		}
break;		break;

case CC_RTO:		case CC_RTO:
/*		/*
* Grab the current time and record it so we know when the		* Grab the current time and record it so we know when the
* most recent congestion event was. Only record it when the		* most recent congestion event was. Only record it when the
* timeout has fired more than once, as there is a reasonable		* timeout has fired more than once, as there is a reasonable
* chance the first one is a false alarm and may not indicate		* chance the first one is a false alarm and may not indicate
* congestion.		* congestion.
*/		*/
if (CCV(ccv, t_rxtshift) >= 2) {		if (CCV(ccv, t_rxtshift) >= 2) {
cubic_data->num_cong_events++;		cubic_data->num_cong_events++;
cubic_data->t_last_cong = ticks;		cubic_data->t_last_cong = ticks;
		ccv->flags &= ~CCF_MAX_CWND;
}		}
break;		break;
}		}
}		}

static void		static void
cubic_conn_init(struct cc_var *ccv)		cubic_conn_init(struct cc_var *ccv)
{		{
struct cubic *cubic_data;		struct cubic *cubic_data;

cubic_data = ccv->cc_data;		cubic_data = ccv->cc_data;

/*		/*
* Ensure we have a sane initial value for max_cwnd recorded. Without		* Ensure we have a sane initial value for max_cwnd recorded. Without
* this here bad things happen when entries from the TCP hostcache		* this here bad things happen when entries from the TCP hostcache
* get used.		* get used.
*/		*/
cubic_data->max_cwnd = CCV(ccv, snd_cwnd);		cubic_data->max_cwnd = CCV(ccv, snd_cwnd);
		ccv->flags \|= CCF_CHG_MAX_CWND;
}		}

static int		static int
cubic_mod_init(void)		cubic_mod_init(void)
{		{

cubic_cc_algo.after_idle = newreno_cc_algo.after_idle;		cubic_cc_algo.after_idle = newreno_cc_algo.after_idle;

return (0);		return (0);
}		}

/*		/*
* Perform any necessary tasks before we exit congestion recovery.		* Perform any necessary tasks before we exit congestion recovery.
*/		*/
static void		static void
cubic_post_recovery(struct cc_var *ccv)		cubic_post_recovery(struct cc_var *ccv)
{		{
struct cubic *cubic_data;		struct cubic *cubic_data;
int pipe;		int pipe;

cubic_data = ccv->cc_data;		cubic_data = ccv->cc_data;
pipe = 0;		pipe = 0;

/* Fast convergence heuristic. */		/* Fast convergence heuristic. */
if (cubic_data->max_cwnd < cubic_data->prev_max_cwnd)		if (cubic_data->max_cwnd < cubic_data->prev_max_cwnd) {
cubic_data->max_cwnd = (cubic_data->max_cwnd * CUBIC_FC_FACTOR)		cubic_data->max_cwnd = (cubic_data->max_cwnd * CUBIC_FC_FACTOR)
>> CUBIC_SHIFT;		>> CUBIC_SHIFT;
		ccv->flags \|= CCF_CHG_MAX_CWND;
		}

if (IN_FASTRECOVERY(CCV(ccv, t_flags))) {		if (IN_FASTRECOVERY(CCV(ccv, t_flags))) {
/*		/*
* If inflight data is less than ssthresh, set cwnd		* If inflight data is less than ssthresh, set cwnd
* conservatively to avoid a burst of data, as suggested in		* conservatively to avoid a burst of data, as suggested in
* the NewReno RFC. Otherwise, use the CUBIC method.		* the NewReno RFC. Otherwise, use the CUBIC method.
*		*
* XXXLAS: Find a way to do this without needing curack		* XXXLAS: Find a way to do this without needing curack
*/		*/
if (V_tcp_do_rfc6675_pipe)		if (V_tcp_do_rfc6675_pipe)
pipe = tcp_compute_pipe(ccv->ccvc.tcp);		pipe = tcp_compute_pipe(ccv->ccvc.tcp);
else		else
pipe = CCV(ccv, snd_max) - ccv->curack;		pipe = CCV(ccv, snd_max) - ccv->curack;

if (pipe < CCV(ccv, snd_ssthresh))		if (pipe < CCV(ccv, snd_ssthresh))
CCV(ccv, snd_cwnd) = pipe + CCV(ccv, t_maxseg);		CCV(ccv, snd_cwnd) = pipe + CCV(ccv, t_maxseg);
else		else
/* Update cwnd based on beta and adjusted max_cwnd. */		/* Update cwnd based on beta and adjusted max_cwnd. */
CCV(ccv, snd_cwnd) = max(1, ((CUBIC_BETA *		CCV(ccv, snd_cwnd) = max(1, ((CUBIC_BETA *
cubic_data->max_cwnd) >> CUBIC_SHIFT));		cubic_data->max_cwnd) >> CUBIC_SHIFT));
}		}
cubic_data->t_last_cong = ticks;		cubic_data->t_last_cong = ticks;
		ccv->flags &= ~CCF_MAX_CWND;

/* Calculate the average RTT between congestion epochs. */		/* Calculate the average RTT between congestion epochs. */
if (cubic_data->epoch_ack_count > 0 &&		if (cubic_data->epoch_ack_count > 0 &&
cubic_data->sum_rtt_ticks >= cubic_data->epoch_ack_count) {		cubic_data->sum_rtt_ticks >= cubic_data->epoch_ack_count) {
cubic_data->mean_rtt_ticks = (int)(cubic_data->sum_rtt_ticks /		cubic_data->mean_rtt_ticks = (int)(cubic_data->sum_rtt_ticks /
cubic_data->epoch_ack_count);		cubic_data->epoch_ack_count);
}		}

cubic_data->epoch_ack_count = 0;		cubic_data->epoch_ack_count = 0;
cubic_data->sum_rtt_ticks = 0;		cubic_data->sum_rtt_ticks = 0;
cubic_data->K = cubic_k(cubic_data->max_cwnd / CCV(ccv, t_maxseg));
}		}

/*		/*
* Record the min RTT and sum samples for the epoch average RTT calculation.		* Record the min RTT and sum samples for the epoch average RTT calculation.
*/		*/
static void		static void
cubic_record_rtt(struct cc_var *ccv)		cubic_record_rtt(struct cc_var *ccv)
{		{
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