From: Jeffrey Altman <jaltman@your-file-system.com>
Date: Mon, 20 Sep 2010 02:48:57 +0000 (-0700)
Subject: Rx: Only backoff the peer timeout once
X-Git-Tag: openafs-devel-1_5_78~134
X-Git-Url: https://git.michaelhowe.org/gitweb/?a=commitdiff_plain;h=e1f1286dc264e186bf3c9ced5b41d7298ed954ad;p=packages%2Fo%2Fopenafs.git

Rx: Only backoff the peer timeout once

If a packet is missing, the peer timeout is backed off to provide
a new starting point for timeout computation.  The backoff state
must be stored in the peer object to ensure that multiple failures
do not result in more than one backoff before a successfully received
packet is available for recomputation.

Change-Id: I6794b3a020801ff421e4ed776afb581962b111a9
Reviewed-on: http://gerrit.openafs.org/2787
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 3b4cad3b78ec5df7253067c70e19c066552d7145)
Reviewed-on: http://gerrit.openafs.org/2808
---

diff --git a/src/rx/rx.c b/src/rx/rx.c
index 923d9b8fc..46b9383c0 100644
--- a/src/rx/rx.c
+++ b/src/rx/rx.c
@@ -3825,7 +3825,6 @@ rxi_ReceiveAckPacket(struct rx_call *call, struct rx_packet *np,
     afs_uint32 skew = 0;
     int nbytes;
     int missing;
-    int backedOff = 0;
     int acked;
     int nNacked = 0;
     int newAckCount = 0;
@@ -4058,14 +4057,14 @@ rxi_ReceiveAckPacket(struct rx_call *call, struct rx_packet *np,
          * timeout value for future packets until a successful response
          * is received for an initial transmission.
          */
-        if (missing && !backedOff) {
+        if (missing && !peer->backedOff) {
             struct clock c = peer->timeout;
             struct clock max_to = {3, 0};
 
             clock_Add(&peer->timeout, &c);
             if (clock_Gt(&peer->timeout, &max_to))
                 peer->timeout = max_to;
-            backedOff = 1;
+            peer->backedOff = 1;
         }
 
 	/* If packet isn't yet acked, and it has been transmitted at least
@@ -6486,6 +6485,9 @@ rxi_ComputeRoundTripTime(struct rx_packet *p,
     clock_Zero(&(peer->timeout));
     clock_Addmsec(&(peer->timeout), rtt_timeout);
 
+    /* Reset the backedOff flag since we just computed a new timeout value */
+    peer->backedOff = 0;
+
     dpf(("rxi_ComputeRoundTripTime(call=%d packet=%"AFS_PTR_FMT" rtt=%d ms, srtt=%d ms, rtt_dev=%d ms, timeout=%d.%06d sec)\n",
           p->header.callNumber, p, MSEC(rttp), peer->rtt >> 3, peer->rtt_dev >> 2, (peer->timeout.sec), (peer->timeout.usec)));
 }
diff --git a/src/rx/rx.h b/src/rx/rx.h
index f75103037..e7c10e88d 100644
--- a/src/rx/rx.h
+++ b/src/rx/rx.h
@@ -401,6 +401,7 @@ struct rx_peer {
     int rtt;			/* Smoothed round trip time, measured in milliseconds/8 */
     int rtt_dev;		/* Smoothed rtt mean difference, in milliseconds/4 */
     struct clock timeout;	/* Current retransmission delay */
+    int backedOff;              /* Has the timeout been backed off due to a missing packet? */
     int nSent;			/* Total number of distinct data packets sent, not including retransmissions */
     int reSends;		/* Total number of retransmissions for this peer, since this structure was created */