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Date:      Thu, 25 May 2017 22:39:48 +0000 (UTC)
From:      Don Lewis <truckman@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org
Subject:   svn commit: r318904 - stable/11/sys/netpfil/ipfw
Message-ID:  <201705252239.v4PMdmQh060331@repo.freebsd.org>

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Author: truckman
Date: Thu May 25 22:39:48 2017
New Revision: 318904
URL: https://svnweb.freebsd.org/changeset/base/318904

Log:
  MFC r318527
  
  Fix the queue delay estimation in PIE/FQ-PIE when the timestamp
  (TS) method is used.  When packet timestamp is used, the "current_qdelay"
  keeps storing the last queue delay value calculated in the dequeue
  function.  Therefore, when a burst of packets arrives followed by
  a pause, the "current_qdelay" will store a high value caused by the
  burst and stick to that value during the pause because the queue
  delay measurement is done inside the dequeue function.  This causes
  the drop probability calculation function to calculate high drop
  probability value instead of zero and prevents the burst allowance
  mechanism from working properly.  Fix this problem by resetting
  "current_qdelay" inside the drop probability calculation function
  when the queue length is zero and TS option is used.
  
  Submitted by:	Rasool Al-Saadi <ralsaadi@swin.edu.au>

Modified:
  stable/11/sys/netpfil/ipfw/dn_aqm_pie.c
  stable/11/sys/netpfil/ipfw/dn_sched_fq_pie.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/netpfil/ipfw/dn_aqm_pie.c
==============================================================================
--- stable/11/sys/netpfil/ipfw/dn_aqm_pie.c	Thu May 25 21:59:19 2017	(r318903)
+++ stable/11/sys/netpfil/ipfw/dn_aqm_pie.c	Thu May 25 22:39:48 2017	(r318904)
@@ -211,11 +211,16 @@ calculate_drop_prob(void *x)
 	pprms = pst->parms;
 	prob = pst->drop_prob;
 
-	/* calculate current qdelay */
-	if (pprms->flags & PIE_DEPRATEEST_ENABLED) {
+	/* calculate current qdelay using DRE method.
+	 * If TS is used and no data in the queue, reset current_qdelay
+	 * as it stays at last value during dequeue process. 
+	*/
+	if (pprms->flags & PIE_DEPRATEEST_ENABLED)
 		pst->current_qdelay = ((uint64_t)pst->pq->ni.len_bytes *
 			pst->avg_dq_time) >> PIE_DQ_THRESHOLD_BITS;
-	}
+	else 
+		if (!pst->pq->ni.len_bytes)
+			 pst->current_qdelay = 0;
 
 	/* calculate drop probability */
 	p = (int64_t)pprms->alpha * 

Modified: stable/11/sys/netpfil/ipfw/dn_sched_fq_pie.c
==============================================================================
--- stable/11/sys/netpfil/ipfw/dn_sched_fq_pie.c	Thu May 25 21:59:19 2017	(r318903)
+++ stable/11/sys/netpfil/ipfw/dn_sched_fq_pie.c	Thu May 25 22:39:48 2017	(r318904)
@@ -383,11 +383,16 @@ fq_calculate_drop_prob(void *x)
 	pprms = pst->parms;
 	prob = pst->drop_prob;
 
-	/* calculate current qdelay */
-	if (pprms->flags & PIE_DEPRATEEST_ENABLED) {
+	/* calculate current qdelay using DRE method.
+	 * If TS is used and no data in the queue, reset current_qdelay
+	 * as it stays at last value during dequeue process.
+	*/
+	if (pprms->flags & PIE_DEPRATEEST_ENABLED)
 		pst->current_qdelay = ((uint64_t)q->stats.len_bytes  * pst->avg_dq_time)
 			>> PIE_DQ_THRESHOLD_BITS;
-	}
+	else
+		if (!q->stats.len_bytes)
+			pst->current_qdelay = 0;
 
 	/* calculate drop probability */
 	p = (int64_t)pprms->alpha * 



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