[SM] not really, given enough capacity, typical streaming protocols
will actually not hit the ceiling, at least the one's I look at every
now and then tend to stay well below actual capacity of the link.
I think DASH type protocol will hit link peaks. An example with iperf
2's burst option a controlled WiFi test rig, server side first.
[root@ctrl1fc35 ~]# iperf -s -i 1 -e --histograms
------------------------------------------------------------
Server listening on TCP port 5001 with pid 23764
Read buffer size: 128 KByte (Dist bin width=16.0 KByte)
Enabled receive histograms bin-width=0.100 ms, bins=10000 (clients
should use --trip-times)
TCP window size: 128 KByte (default)
------------------------------------------------------------
[ 1] local 192.168.1.15%enp2s0 port 5001 connected with 192.168.1.234
port 34894 (burst-period=1.00s) (trip-times) (sock=4) (peer 2.1.9-rc2)
(icwnd/mss/irtt=14/1448/5170) on 2023-03-13 11:37:24.500 (PDT)
[ ID] Burst (start-end) Transfer Bandwidth XferTime (DC%)
Reads=Dist NetPwr
[ 1] 0.00-0.13 sec 10.0 MBytes 633 Mbits/sec 132.541 ms (13%)
209=29:31:31:88:11:2:1:16 597
[ 1] 1.00-1.11 sec 10.0 MBytes 755 Mbits/sec 111.109 ms (11%)
205=34:30:22:83:11:2:6:17 849
[ 1] 2.00-2.12 sec 10.0 MBytes 716 Mbits/sec 117.196 ms (12%)
208=33:39:20:81:13:1:5:16 763
[ 1] 3.00-3.11 sec 10.0 MBytes 745 Mbits/sec 112.564 ms (11%)
203=27:36:30:76:6:3:6:19 828
[ 1] 4.00-4.11 sec 10.0 MBytes 787 Mbits/sec 106.621 ms (11%)
193=29:26:19:80:10:4:6:19 922
[ 1] 5.00-5.11 sec 10.0 MBytes 769 Mbits/sec 109.148 ms (11%)
208=36:25:32:86:6:1:5:17 880
[ 1] 6.00-6.11 sec 10.0 MBytes 760 Mbits/sec 110.403 ms (11%)
206=42:30:22:73:8:3:5:23 860
[ 1] 7.00-7.11 sec 10.0 MBytes 775 Mbits/sec 108.261 ms (11%)
171=20:21:21:58:12:1:11:27 895
[ 1] 8.00-8.11 sec 10.0 MBytes 746 Mbits/sec 112.405 ms (11%)
203=36:31:28:70:9:3:2:24 830
[ 1] 9.00-9.11 sec 10.0 MBytes 748 Mbits/sec 112.133 ms (11%)
228=41:56:27:73:7:2:3:19 834
[ 1] 0.00-10.00 sec 100 MBytes 83.9 Mbits/sec
113.238/106.621/132.541/7.367 ms 2034=327:325:252:768:93:22:50:197
[ 1] 0.00-10.00 sec F8(f)-PDF:
bin(w=100us):cnt(10)=1067:1,1083:1,1092:1,1105:1,1112:1,1122:1,1125:1,1126:1,1172:1,1326:1
(5.00/95.00/99.7%=1067/1326/1326,Outliers=0,obl/obu=0/0) (132.541
ms/1678732644.500333)
[root@fedora ~]# iperf -c 192.168.1.15 -i 1 -t 10 --burst-size 10M
--burst-period 1 --trip-times
------------------------------------------------------------
Client connecting to 192.168.1.15, TCP port 5001 with pid 132332 (1
flows)
Write buffer size: 131072 Byte
Bursting: 10.0 MByte every 1.00 second(s)
TOS set to 0x0 (Nagle on)
TCP window size: 16.0 KByte (default)
Event based writes (pending queue watermark at 16384 bytes)
------------------------------------------------------------
[ 1] local 192.168.1.234%eth1 port 34894 connected with 192.168.1.15
port 5001 (prefetch=16384) (trip-times) (sock=3)
(icwnd/mss/irtt=14/1448/5489) (ct=5.58 ms) on 2023-03-13 11:37:24.494
(PDT)
[ ID] Interval Transfer Bandwidth Write/Err Rtry
Cwnd/RTT(var) NetPwr
[ 1] 0.00-1.00 sec 10.0 MBytes 83.9 Mbits/sec 80/0 0
5517K/18027(1151) us 582
[ 1] 1.00-2.00 sec 10.0 MBytes 83.9 Mbits/sec 80/0 0
5584K/13003(2383) us 806
[ 1] 2.00-3.00 sec 10.0 MBytes 83.9 Mbits/sec 80/0 0
5613K/16462(962) us 637
[ 1] 3.00-4.00 sec 10.0 MBytes 83.9 Mbits/sec 80/0 0
5635K/19523(671) us 537
[ 1] 4.00-5.00 sec 10.0 MBytes 83.9 Mbits/sec 80/0 0
5594K/10013(1685) us 1047
[ 1] 5.00-6.00 sec 10.0 MBytes 83.9 Mbits/sec 80/0 0
5479K/14008(654) us 749
[ 1] 6.00-7.00 sec 10.0 MBytes 83.9 Mbits/sec 80/0 0
5613K/17752(283) us 591
[ 1] 7.00-8.00 sec 10.0 MBytes 83.9 Mbits/sec 80/0 0
5599K/17743(436) us 591
[ 1] 8.00-9.00 sec 10.0 MBytes 83.9 Mbits/sec 80/0 0
5577K/11214(2538) us 935
[ 1] 9.00-10.00 sec 10.0 MBytes 83.9 Mbits/sec 80/0 0
4178K/7251(993) us 1446
[ 1] 0.00-10.01 sec 100 MBytes 83.8 Mbits/sec 800/0 0
4178K/7725(1694) us 1356
[root@fedora ~]#
Note: Client side output is being updated to support outputs based upon
the bursts. This allows one to see that a DASH type protocol can drive
the bw bottleneck queue.
Bob
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