rx: Don't call gettimeofday for every packet ack

Every time we receive an ACK packet, we call gettimeofday() for
every entry in the transmit queue that's permanently ack'd by that
packet. Instead, just make a note of the time when we start
processing the packet queue, and use it for every packet in the
queue.

This shaves around 5% off rxperf's runtime with a window size of 128.

Change-Id: I65c705c575c4a470b49390e7efca33c279a3133c
Reviewed-on: http://gerrit.openafs.org/2956
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>

diff --git a/src/rx/rx.c b/src/rx/rx.c
index 5144b7beedf1e32f3556427027264999a005cdf7..ff4b56470e8702d7682e9ccdd03141e320b34f66 100644 (file)
--- a/src/rx/rx.c
+++ b/src/rx/rx.c
@@ -129,6 +129,9 @@ int (*swapNameProgram) (PROCESS, const char *, char *) = 0;
 
 /* Local static routines */
 static void rxi_DestroyConnectionNoLock(struct rx_connection *conn);
+static void rxi_ComputeRoundTripTime(struct rx_packet *, struct clock *,
+                                    struct rx_peer *, struct clock *);
+
 #ifdef RX_ENABLE_LOCKS
 static void rxi_SetAcksInTransmitQueue(struct rx_call *call);
 #endif
@@ -3858,7 +3861,8 @@ rx_ack_reason(int reason)
  */
 static void
 rxi_ComputePeerNetStats(struct rx_call *call, struct rx_packet *p,
-                       struct rx_ackPacket *ap, struct rx_packet *np)
+                       struct rx_ackPacket *ap, struct rx_packet *np,
+                       struct clock *now)
 {
     struct rx_peer *peer = call->conn->peer;
 
@@ -3867,7 +3871,7 @@ rxi_ComputePeerNetStats(struct rx_call *call, struct rx_packet *p,
     if (!(p->flags & RX_PKTFLAG_ACKED) &&
         ap->reason != RX_ACK_DELAY &&
         clock_Eq(&p->timeSent, &p->firstSent))
-       rxi_ComputeRoundTripTime(p, &p->timeSent, peer);
+       rxi_ComputeRoundTripTime(p, &p->timeSent, peer, now);
 #ifdef ADAPT_WINDOW
     rxi_ComputeRate(peer, call, p, np, ap->reason);
 #endif
@@ -3884,6 +3888,7 @@ rxi_ReceiveAckPacket(struct rx_call *call, struct rx_packet *np,
     struct rx_packet *nxp;     /* Next packet pointer for queue_Scan */
     struct rx_connection *conn = call->conn;
     struct rx_peer *peer = conn->peer;
+    struct clock now;          /* Current time, for RTT calculations */
     afs_uint32 first;
     afs_uint32 serial;
     /* because there are CM's that are bogus, sending weird values for this. */
@@ -4017,11 +4022,14 @@ rxi_ReceiveAckPacket(struct rx_call *call, struct rx_packet *np,
      * acknowledged as having been sent to the peer's upper level.
      * All other packets must be retained.  So only packets with
      * sequence numbers < ap->firstPacket are candidates. */
+
+    clock_GetTime(&now);
+
     for (queue_Scan(&call->tq, tp, nxp, rx_packet)) {
        if (tp->header.seq >= first)
            break;
        call->tfirst = tp->header.seq + 1;
-        rxi_ComputePeerNetStats(call, tp, ap, np);
+        rxi_ComputePeerNetStats(call, tp, ap, np, &now);
        if (!(tp->flags & RX_PKTFLAG_ACKED)) {
            newAckCount++;
        }
@@ -4083,7 +4091,7 @@ rxi_ReceiveAckPacket(struct rx_call *call, struct rx_packet *np,
        if (tp->header.seq >= first)
 #endif /* RX_ENABLE_LOCKS */
 #endif /* AFS_GLOBAL_RXLOCK_KERNEL */
-            rxi_ComputePeerNetStats(call, tp, ap, np);
+            rxi_ComputePeerNetStats(call, tp, ap, np, &now);
 
        /* Set the acknowledge flag per packet based on the
         * information in the ack packet. An acknowlegded packet can
@@ -6465,21 +6473,20 @@ rxi_ChallengeOn(struct rx_connection *conn)
 
 /* rxi_ComputeRoundTripTime is called with peer locked. */
 /* sentp and/or peer may be null */
-void
+static void
 rxi_ComputeRoundTripTime(struct rx_packet *p,
                         struct clock *sentp,
-                        struct rx_peer *peer)
+                        struct rx_peer *peer,
+                        struct clock *now)
 {
     struct clock thisRtt, *rttp = &thisRtt;
-
     int rtt_timeout;
 
-    clock_GetTime(rttp);
+    thisRtt = *now;
 
-    if (clock_Lt(rttp, sentp)) {
-       clock_Zero(rttp);
+    if (clock_Lt(rttp, sentp))
        return;                 /* somebody set the clock back, don't count this time. */
-    }
+
     clock_Sub(rttp, sentp);
     dpf(("rxi_ComputeRoundTripTime(call=%d packet=%"AFS_PTR_FMT" rttp=%d.%06d sec)\n",
           p->header.callNumber, p, rttp->sec, rttp->usec));

diff --git a/src/rx/rx_prototypes.h b/src/rx/rx_prototypes.h
index ae75deaac127a303f06db9847bc36e2594f672a5..afaa00f547099bcfa93de61286595b692de9e4b4 100644 (file)
--- a/src/rx/rx_prototypes.h
+++ b/src/rx/rx_prototypes.h
@@ -181,9 +181,6 @@ extern void rxi_ChallengeEvent(struct rxevent *event,
                               void *conn, /* struct rx_connection *conn */
                               void *arg1, int atries);
 extern void rxi_ChallengeOn(struct rx_connection *conn);
-extern void rxi_ComputeRoundTripTime(struct rx_packet *p,
-                                    struct clock *sentp,
-                                    struct rx_peer *peer);
 extern void rxi_ReapConnections(struct rxevent *unused, void *unused1,
                                void *unused2);
 extern int rxs_Release(struct rx_securityClass *aobj);