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Followup to previous commit..

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- It's worthwhile to use untimeout(9), even though we must still protect
  against "false" timeouts, because most of the time it saves having to
  handle a dummy timeout event.
- Slight tweaks to the delayed ACK algorithm paramters.
This commit is contained in:
Archie Cobbs 2000-07-25 18:57:20 +00:00
parent 01ba8e704f
commit da010626df
1 changed files with 40 additions and 20 deletions
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60
sys/netgraph/ng_pptpgre.c
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@ -121,9 +121,16 @@ typedef u_int64_t pptptime_t;
/* Acknowledgment timeout parameters and functions */
#define PPTP_XMIT_WIN 16 /* max xmit window */
#define PPTP_MIN_RTT (PPTP_TIME_SCALE / 10) /* 100 milliseconds */
#define PPTP_MIN_TIMEOUT (PPTP_TIME_SCALE / 100) /* 10 milliseconds */
#define PPTP_MIN_TIMEOUT (PPTP_TIME_SCALE / 500) /* 2 milliseconds */
#define PPTP_MAX_TIMEOUT (10 * PPTP_TIME_SCALE) /* 10 seconds */
/* When we recieve a packet, we wait to see if there's an outgoing packet
we can piggy-back the ACK off of. These parameters determine the mimimum
and maxmimum length of time we're willing to wait in order to do that.
These have no effect unless "enableDelayedAck" is turned on. */
#define PPTP_MIN_ACK_DELAY (PPTP_TIME_SCALE / 500) /* 2 milliseconds */
#define PPTP_MAX_ACK_DELAY (PPTP_TIME_SCALE / 2) /* 500 milliseconds */
/* See RFC 2637 section 4.4 */
#define PPTP_ACK_ALPHA(x) ((x) >> 3) /* alpha = 0.125 */
#define PPTP_ACK_BETA(x) ((x) >> 2) /* beta = 0.25 */
@ -145,16 +152,11 @@ struct ng_pptpgre_ackp {
u_int32_t winAck; /* seq when xmitWin will grow */
pptptime_t timeSent[PPTP_XMIT_WIN];
#ifdef DEBUG_RAT
pptptime_t timerStart;
pptptime_t timerLength;
pptptime_t timerStart; /* when rackTimer started */
pptptime_t timerLength; /* rackTimer duration */
#endif
};
/* When we recieve a packet, we wait to see if there's an outgoing packet
we can piggy-back the ACK off of. These parameters determine the mimimum
and maxmimum length of time we're willing to wait in order to do that. */
#define PPTP_MAX_ACK_DELAY ((int) (0.25 * PPTP_TIME_SCALE))
/* Node private data */
struct ng_pptpgre_private {
hook_p upper; /* hook to upper layers */
@ -181,7 +183,7 @@ static ng_disconnect_t ng_pptpgre_disconnect;
/* Helper functions */
static int ng_pptpgre_xmit(node_p node, struct mbuf *m, meta_p meta);
static int ng_pptpgre_recv(node_p node, struct mbuf *m, meta_p meta);
static void ng_pptpgre_start_send_ack_timer(node_p node, long ackTimeout);
static void ng_pptpgre_start_send_ack_timer(node_p node, int ackTimeout);
static void ng_pptpgre_start_recv_ack_timer(node_p node);
static void ng_pptpgre_recv_ack_timeout(void *arg);
static void ng_pptpgre_send_ack_timeout(void *arg);
@ -515,7 +517,11 @@ ng_pptpgre_xmit(node_p node, struct mbuf *m, meta_p meta)
gre->hasAck = 1;
gre->data[gre->hasSeq] = htonl(priv->recvSeq);
priv->xmitAck = priv->recvSeq;
a->sackTimerPtr = NULL;
if (a->sackTimerPtr != NULL) {
untimeout(ng_pptpgre_send_ack_timeout,
a->sackTimerPtr, a->sackTimer);
a->sackTimerPtr = NULL;
}
}
/* Prepend GRE header to outgoing frame */
@ -547,7 +553,7 @@ ng_pptpgre_xmit(node_p node, struct mbuf *m, meta_p meta)
/* Deliver packet */
NG_SEND_DATA(error, priv->lower, m, meta);
/* Start send ACK timer */
/* Start receive ACK timer if data was sent and not already running */
if (error == 0 && gre->hasSeq && priv->xmitSeq == priv->recvAck + 1)
ng_pptpgre_start_recv_ack_timer(node);
return (error);
@ -667,7 +673,11 @@ ng_pptpgre_recv(node_p node, struct mbuf *m, meta_p meta)
}
/* Stop/(re)start receive ACK timer as necessary */
a->rackTimerPtr = NULL;
if (a->rackTimerPtr != NULL) {
untimeout(ng_pptpgre_recv_ack_timeout,
a->rackTimerPtr, a->rackTimer);
a->rackTimerPtr = NULL;
}
if (priv->recvAck != priv->xmitSeq)
ng_pptpgre_start_recv_ack_timer(node);
}
@ -690,13 +700,14 @@ ng_pptpgre_recv(node_p node, struct mbuf *m, meta_p meta)
/* We need to acknowledge this packet; do it soon... */
if (a->sackTimerPtr == NULL) {
long maxWait;
int maxWait;
/* Take half of the estimated round trip time */
maxWait = (a->rtt >> 1);
/* Take 1/4 of the estimated round trip time */
maxWait = (a->rtt >> 2);
/* If delayed ACK is disabled, send it now */
if (!priv->conf.enableDelayedAck || maxWait == 0)
if (!priv->conf.enableDelayedAck
|| maxWait < PPTP_MIN_ACK_DELAY)
ng_pptpgre_xmit(node, NULL, NULL);
else { /* send the ack later */
if (maxWait > PPTP_MAX_ACK_DELAY)
@ -738,6 +749,7 @@ ng_pptpgre_start_recv_ack_timer(node_p node)
/* Compute how long until oldest unack'd packet times out,
and reset the timer to that time. */
KASSERT(a->rackTimerPtr == NULL, ("%s: rackTimer", __FUNCTION__));
remain = (a->timeSent[0] + a->ato) - ng_pptpgre_time(node);
if (remain < 0)
remain = 0;
@ -817,7 +829,7 @@ ng_pptpgre_recv_ack_timeout(void *arg)
* already running.
*/
static void
ng_pptpgre_start_send_ack_timer(node_p node, long ackTimeout)
ng_pptpgre_start_send_ack_timer(node_p node, int ackTimeout)
{
const priv_p priv = node->private;
struct ng_pptpgre_ackp *const a = &priv->ackp;
@ -911,9 +923,17 @@ ng_pptpgre_reset(node_p node)
/* Reset stats */
bzero(&priv->stats, sizeof(priv->stats));
/* "Stop" timers */
a->sackTimerPtr = NULL;
a->rackTimerPtr = NULL;
/* Stop timers */
if (a->sackTimerPtr != NULL) {
untimeout(ng_pptpgre_send_ack_timeout,
a->sackTimerPtr, a->sackTimer);
a->sackTimerPtr = NULL;
}
if (a->rackTimerPtr != NULL) {
untimeout(ng_pptpgre_recv_ack_timeout,
a->rackTimerPtr, a->rackTimer);
a->rackTimerPtr = NULL;
}
}
/*