[openib-general] [PATCH/RFC] IB/ipoib: add selective tx signaling - performance measurements

[Moni Shoua]

Tests with iperf and netperf for unicast and multicast destinations show
an improvement in the ability of user applications to xmit packets. 

Examples: Number of successful writes as reported by 30 seconds UDP_STREAM of 100 byte packets.
Tested with netperf on Dual CPU (64bit Intel Xeon 3GHz) running linux-2.6.20-rc1 (sender) and
OFED-1.1 (receiver)

Note that the results below show improvement only for TX so we see an end to end packet loss.
Improving the receiver (NAPI) will reduce the packet loss. 

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Without the patch
PPS=230507

linux:~ # netperf -H 192.168.11.234 -t UDP_STREAM -l 30 -- -m 100
UDP UNIDIRECTIONAL SEND TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.11.234 (192.168.11.234) port 0 AF_INET
Socket  Message  Elapsed      Messages
Size    Size     Time         Okay Errors   Throughput
bytes   bytes    secs            #      #   10^6bits/sec

262144     100   30.00     6915225      0     184.40
135168           30.00     6366068            169.75

----------------------------------------------------------------------
tx_signal_rate=1
PPS=244116

linux:~ # netperf -H 192.168.11.234 -t UDP_STREAM -l 30 -- -m 100
UDP UNIDIRECTIONAL SEND TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.11.234 (192.168.11.234) port 0 AF_INET
Socket  Message  Elapsed      Messages
Size    Size     Time         Okay Errors   Throughput
bytes   bytes    secs            #      #   10^6bits/sec

262144     100   30.00     7323482      0     195.27
135168           30.00     6905764            184.13

----------------------------------------------------------------------
tx_signal_rate=4
PPS=254748

linux:~ # netperf -H 192.168.11.234 -t UDP_STREAM -l 30 -- -m 100
UDP UNIDIRECTIONAL SEND TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.11.234 (192.168.11.234) port 0 AF_INET
Socket  Message  Elapsed      Messages
Size    Size     Time         Okay Errors   Throughput
bytes   bytes    secs            #      #   10^6bits/sec

262144     100   30.00     7642461      0     203.77
135168           30.00     6741080            179.74

----------------------------------------------------------------------
tx_signal_rate=8
PPS=278458

linux:~ # netperf -H 192.168.11.234 -t UDP_STREAM -l 30 -- -m 100
UDP UNIDIRECTIONAL SEND TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.11.234 (192.168.11.234) port 0 AF_INET
Socket  Message  Elapsed      Messages
Size    Size     Time         Okay Errors   Throughput
bytes   bytes    secs            #      #   10^6bits/sec

262144     100   30.01     8353760      0     222.73
135168           30.01     6884056            183.54

----------------------------------------------------------------------
tx_signal_rate=16
PPS=316418

linux:~ # netperf -H 192.168.11.234 -t UDP_STREAM -l 30 -- -m 100
UDP UNIDIRECTIONAL SEND TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.11.234 (192.168.11.234) port 0 AF_INET
Socket  Message  Elapsed      Messages
Size    Size     Time         Okay Errors   Throughput
bytes   bytes    secs            #      #   10^6bits/sec

262144     100   30.00     9492551      0     253.11
135168           30.00     6501771            173.37

----------------------------------------------------------------------
tx_signal_rate=32
PPS=328316

linux:~ # netperf -H 192.168.11.234 -t UDP_STREAM -l 30 -- -m 100
UDP UNIDIRECTIONAL SEND TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.11.234 (192.168.11.234) port 0 AF_INET
Socket  Message  Elapsed      Messages
Size    Size     Time         Okay Errors   Throughput
bytes   bytes    secs            #      #   10^6bits/sec

262144     100   30.00     9849480      0     262.62
135168           30.00     6006394            160.15

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