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• Application process never terminates on each run

  - by rockyurock

  I am seeing an application always remains live even after closing the application using my Perl script below. Also, for the subsequent runs, it always says that "The process cannot access the file because it is being used by another process. iperf.exe -u -s -p 5001 successful. Output was:" So every time I have to change the file name $file used in script or I have to kill the iperf.exe process in the Task Manager. Could anybody please let me know the way to get rid of it? Here is the code I am using ... my @command_output; eval { my $file = "abc6.txt"; $command = "iperf.exe -u -s -p 5001"; alarm 10; system("$command > $file"); alarm 0; close $file; }; if ($@) { warn "$command timed out.\n"; } else { print "$command successful. Output was:\n", $file; } unlink $file;

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• Slower than expected 802.11n wireless network speeds

  - by Ian

  I have two ASUS laptops running Windows 7 connected wirelessly via 802.11n at 150 Mbit, as reported by Task Manager. The router is Netgear WNDR3700. When testing the wireless connection speed using iperf, I'm not getting nearly 150 Mbit: C:\>iperf -c 10.0.0.123 -t 30 ------------------------------------------------------------ Client connecting to 10.0.0.123, TCP port 5001 TCP window size: 8.00 KByte (default) ------------------------------------------------------------ [148] local 10.0.0.116 port 53819 connected with 10.0.0.123 port 5001 [ ID] Interval Transfer Bandwidth [148] 0.0-30.0 sec 41.2 MBytes 11.5 Mbits/sec That's a typical result. Running parallel client threads does not increase the overall total speed. Why would I only be getting 11.5 Mbit on a 150 Mbit connection?

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• What can impact the throughput rate at tcp or Os level?

  - by Jimm

  I am facing a problem, where running the same application on different servers, yields unexpected performance results. For example, running the application on a particular faster server (faster cpu, more memory), with no load, yields slower performance than running on a less powerful server on the same network. I am suspecting that either OS or TCP is causing the slowness on the faster server. I cannot use IPerf , unless i modify it, because the "performance" in my application is defined as Component A sends a message to Component B. Component B sends an ACK to component A and ONLY then Component A would send the next message. So it is different from what IPerf does, which to my knowledge, simply tries to push as many messages as possible. Is there a tool that can look at OS and TCP configuration and suggest the cause of slowness?

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• How To Get The Outout of Win32::Process command in perl

  - by rockyurock

  hello all, i am using "use Win32::Process" for my application run as below, it runs fine but i did not get any way to get the output to a .txt file. i used NORMAL_PRIORITY_CLASS rather than CREATE_NEW_CONSOLE to get the output on the same terminal itself but i don't know how to redirect it to a txt file. /rocky !/usr/bin/perl use strict; use warnings; use Win32::Process; Win32::Process::Create(my $ProcessObj, "iperf.exe", "iperf.exe -u -s -p 5001", 0, NORMAL_PRIORITY_CLASS, ".") || die ErrorReport(); my @command_output; push @command_output,$ProcessObj; open FILE, "zz.txt" or die $!; print FILE @command_output; close FILE; sleep 10; $ProcessObj-Kill(0); sub ErrorReport{ print Win32::FormatMessage( Win32::GetLastError() ); }

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• How do I get the output of Win32::Process command in Perl?

  - by rockyurock

  I am using use Win32::Process for my application run as below. It runs fine, but I did not get any way to get the output to a .txt file. I used NORMAL_PRIORITY_CLASS rather than CREATE_NEW_CONSOLE to get the output on the same terminal itself, but I don't know how to redirect it to a txt file. /rocky #!/usr/bin/perl use strict; use warnings; use Win32::Process; Win32::Process::Create(my $ProcessObj, "iperf.exe", "iperf.exe -u -s -p 5001", 0, NORMAL_PRIORITY_CLASS, ".") || die ErrorReport(); my @command_output; push @command_output,$ProcessObj; open FILE, ">zz.txt" or die $!; print FILE @command_output; close FILE; sleep 10; $ProcessObj->Kill(0); sub ErrorReport{ print Win32::FormatMessage( Win32::GetLastError() ); }

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• Linux Experts Riddle: Network output of 10MB/s on 10GB/s NIC

  - by user150324

  I have two CentOS 6 servers. I am trying to transfer files between them. Source server has 10GB/s NIC nd destination server has 1GB/s NIC. Regardless to the command used nor the protocol, the transfer speed is ~1 Mega byte per second. The goal is at least couple dozens MB per second. I have tried: rsync (also with various encryptions), scp, wget, aftp, nc. Here's some testing results with iperf: [root@serv ~]# iperf -c XXX.XXX.XXX.XXX -i 1 ------------------------------------------------------------ Client connecting to XXX.XXX.XXX.XXX, TCP port 5001 TCP window size: 64.0 KByte (default) ------------------------------------------------------------ [ 3] local XXX.XXX.XXX.XXX port 33180 connected with XXX.XXX.XXX.XXX port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0- 1.0 sec 1.30 MBytes 10.9 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 1.0- 2.0 sec 1.28 MBytes 10.7 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 2.0- 3.0 sec 1.34 MBytes 11.3 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 3.0- 4.0 sec 1.53 MBytes 12.8 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 4.0- 5.0 sec 1.65 MBytes 13.8 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 5.0- 6.0 sec 1.79 MBytes 15.0 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 6.0- 7.0 sec 1.95 MBytes 16.3 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 7.0- 8.0 sec 1.98 MBytes 16.6 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 8.0- 9.0 sec 1.91 MBytes 16.0 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 9.0-10.0 sec 2.05 MBytes 17.2 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 1.68 MBytes 14.0 Mbits/sec I guess HD is not the bottleneck here.

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• Why is my rsync so slow?

  - by iblue

  My Laptop and my workstation are both connected to a Gigabit Switch. Both are running Linux. But when I copy files with rsync, it performs badly. I get about 22 MB/s. Shouldn't I theoretically get about 125 MB/s? What is the limiting factor here? EDIT: I conducted some experiments. Write performance on the laptop The laptop has a xfs filesystem with full disk encryption. It uses aes-cbc-essiv:sha256 cipher mode with 256 bits key length. Disk write performance is 58.8 MB/s. iblue@nerdpol:~$ LANG=C dd if=/dev/zero of=test.img bs=1M count=1024 1073741824 Bytes (1.1 GB) copied, 18.2735 s, 58.8 MB/s Read performance on the workstation The files I copied are on a software RAID-5 over 5 HDDs. On top of the raid is a lvm. The volume itself is encrypted with the same cipher. The workstation has a FX-8150 cpu that has a native AES-NI instruction set which speeds up encryption. Disk read performance is 256 MB/s (cache was cold). iblue@raven:/mnt/bytemachine/imgs$ dd if=backup-1333796266.tar.bz2 of=/dev/null bs=1M 10213172008 bytes (10 GB) copied, 39.8882 s, 256 MB/s Network performance I ran iperf between the two clients. Network performance is 939 Mbit/s iblue@raven $ iperf -c 94.135.XXX ------------------------------------------------------------ Client connecting to 94.135.XXX, TCP port 5001 TCP window size: 23.2 KByte (default) ------------------------------------------------------------ [ 3] local 94.135.XXX port 59385 connected with 94.135.YYY port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 1.09 GBytes 939 Mbits/sec

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• Improving TCP performance over a gigabit network lots of connections and high traffic for storage and streaming services

  - by Linux Guy

  I have two servers, Both servers hardware Specification are Processor : Dual Processor RAM : over 128 G.B Hard disk : SSD Hard disk Outging Traffic bandwidth : 3 Gbps network cards speed : 10 Gbps Server A : for Encoding videos Server B : for storage videos andstream videos over web interface like youtube The inbound bandwidth between two servers is 10Gbps , the outbound bandwidth internet bandwidth is 500Mpbs Both servers using public ip addresses in public and private network Both servers transfer and connection on nginx port , and the server B used for streaming media , like youtube stream videos Both servers in same network , when i do ping from Server A to Server B i got high time latency above 1.0ms , the time range time=52.7 ms to time=215.7 ms - This is the output of iftop utility 353Mb 707Mb 1.04Gb 1.38Gb 1.73Gb mqqqqqqqqqqqqqqqqqqqqqqqqqqqvqqqqqqqqqqqqqqqqqqqqqqqqqqqvqqqqqqqqqqqqqqqqqqqqqqqqqqqvqqqqqqqqqqqqqqqqqqqqqqqqqqqvqqqqqqqqqqqqqqqqqqqqqqqqqqq server.example.com => ip.address 6.36Mb 4.31Mb 1.66Mb <= 158Kb 94.8Kb 35.1Kb server.example.com => ip.address 1.23Mb 4.28Mb 1.12Mb <= 17.1Kb 83.5Kb 21.9Kb server.example.com => ip.address 395Kb 3.89Mb 1.07Mb <= 6.09Kb 109Kb 28.6Kb server.example.com => ip.address 4.55Mb 3.83Mb 1.04Mb <= 55.6Kb 45.4Kb 13.0Kb server.example.com => ip.address 649Kb 3.38Mb 1.47Mb <= 9.00Kb 38.7Kb 16.7Kb server.example.com => ip.address 5.00Mb 3.32Mb 1.80Mb <= 65.7Kb 55.1Kb 29.4Kb server.example.com => ip.address 387Kb 3.13Mb 1.06Mb <= 18.4Kb 39.9Kb 15.0Kb server.example.com => ip.address 3.27Mb 3.11Mb 1.01Mb <= 81.2Kb 64.5Kb 20.9Kb server.example.com => ip.address 1.75Mb 3.08Mb 2.72Mb <= 16.6Kb 35.6Kb 32.5Kb server.example.com => ip.address 1.75Mb 2.90Mb 2.79Mb <= 22.4Kb 32.6Kb 35.6Kb server.example.com => ip.address 3.03Mb 2.78Mb 1.82Mb <= 26.6Kb 27.4Kb 20.2Kb server.example.com => ip.address 2.26Mb 2.66Mb 1.36Mb <= 51.7Kb 49.1Kb 24.4Kb server.example.com => ip.address 586Kb 2.50Mb 1.03Mb <= 4.17Kb 26.1Kb 10.7Kb server.example.com => ip.address 2.42Mb 2.49Mb 2.44Mb <= 31.6Kb 29.7Kb 29.9Kb server.example.com => ip.address 2.41Mb 2.46Mb 2.41Mb <= 26.4Kb 24.5Kb 23.8Kb server.example.com => ip.address 2.37Mb 2.39Mb 2.40Mb <= 28.9Kb 27.0Kb 28.5Kb server.example.com => ip.address 525Kb 2.20Mb 1.05Mb <= 7.03Kb 26.0Kb 12.8Kb qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq TX: cum: 102GB peak: 1.65Gb rates: 1.46Gb 1.44Gb 1.48Gb RX: 1.31GB 24.3Mb 19.5Mb 18.9Mb 20.0Mb TOTAL: 103GB 1.67Gb 1.48Gb 1.46Gb 1.50Gb I check the transfer speed using iperf utility From Server A to Server B # iperf -c 0.0.0.2 -p 8777 ------------------------------------------------------------ Client connecting to 0.0.0.2, TCP port 8777 TCP window size: 85.3 KByte (default) ------------------------------------------------------------ [ 3] local 0.0.0.1 port 38895 connected with 0.0.0.2 port 8777 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.8 sec 528 KBytes 399 Kbits/sec My Current Connections in Server B # netstat -an|grep ":8777"|awk '/tcp/ {print $6}'|sort -nr| uniq -c 2072 TIME_WAIT 28 SYN_RECV 1 LISTEN 189 LAST_ACK 139 FIN_WAIT2 373 FIN_WAIT1 3381 ESTABLISHED 34 CLOSING Server A Network Card Information Settings for eth0: Supported ports: [ TP ] Supported link modes: 100baseT/Full 1000baseT/Full 10000baseT/Full Supported pause frame use: No Supports auto-negotiation: Yes Advertised link modes: 10000baseT/Full Advertised pause frame use: No Advertised auto-negotiation: Yes Speed: 10000Mb/s Duplex: Full Port: Twisted Pair PHYAD: 0 Transceiver: external Auto-negotiation: on MDI-X: Unknown Supports Wake-on: d Wake-on: d Current message level: 0x00000007 (7) drv probe link Link detected: yes Server B Network Card Information Settings for eth2: Supported ports: [ FIBRE ] Supported link modes: 10000baseT/Full Supported pause frame use: No Supports auto-negotiation: No Advertised link modes: 10000baseT/Full Advertised pause frame use: No Advertised auto-negotiation: No Speed: 10000Mb/s Duplex: Full Port: Direct Attach Copper PHYAD: 0 Transceiver: external Auto-negotiation: off Supports Wake-on: d Wake-on: d Current message level: 0x00000007 (7) drv probe link Link detected: yes ifconfig server A eth0 Link encap:Ethernet HWaddr 00:25:90:ED:9E:AA inet addr:0.0.0.1 Bcast:0.0.0.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1202795665 errors:0 dropped:64334 overruns:0 frame:0 TX packets:2313161968 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:893413096188 (832.0 GiB) TX bytes:3360949570454 (3.0 TiB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:2207544 errors:0 dropped:0 overruns:0 frame:0 TX packets:2207544 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:247769175 (236.2 MiB) TX bytes:247769175 (236.2 MiB) ifconfig Server B eth2 Link encap:Ethernet HWaddr 00:25:90:82:C4:FE inet addr:0.0.0.2 Bcast:0.0.0.2 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:39973046980 errors:0 dropped:1828387600 overruns:0 frame:0 TX packets:69618752480 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:3013976063688 (2.7 TiB) TX bytes:102250230803933 (92.9 TiB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:1049495 errors:0 dropped:0 overruns:0 frame:0 TX packets:1049495 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:129012422 (123.0 MiB) TX bytes:129012422 (123.0 MiB) Netstat -i on Server B # netstat -i Kernel Interface table Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg eth2 9000 0 42098629968 0 2131223717 0 73698797854 0 0 0 BMRU lo 65536 0 1077908 0 0 0 1077908 0 0 0 LRU I Turn up send/receive buffers on the network card to 2048 and problem still persist I increase the MTU for server A and problem still persist and i increase the MTU for server B for better connectivity and transfer speed but it couldn't transfer at all The problem is : as you can see from iperf utility, the transfer speed from server A to server B slow when i restart network service in server B the transfer in server A at full speed, after 2 minutes , it's getting slow How could i troubleshoot slow speed issue and fix it in server B ? Notice : if there any other commands i should execute in servers for more information, so it might help resolve the problem , let me know in comments

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• How can I terminate a system command with alarm in Perl?

  - by rockyurock

  I am running the below code snippet on Windows. The server starts listening continuously after reading from client. I want to terminate this command after a time period. If I use alarm() function call within main.pl, then it terminates the whole Perl program (here main.pl), so I called this system command by placing it in a separate Perl file and calling this Perl file (alarm.pl) in the original Perl File using the system command. But in this way I was unable to take the output of this system() call neither in the original Perl File nor in called one Perl File. Could anybody please let me know the way to terminate a system() call or take the output in that way I used above? main.pl my @output = system("alarm.pl"); print"one iperf completed\n"; open FILE, ">display.txt" or die $!; print FILE @output_1; close FILE; alarm.pl alarm 30; my @output_1 = readpipe("adb shell cd /data/app; ./iperf -u -s -p 5001"); open FILE, ">display.txt" or die $!; print FILE @output_1; close FILE; In both ways display.txt is always empty.

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• Symfony - Several form on the same page -> ID issue

  - by Julien

  Hi folks. I have an issue while displaying several forms of the same model on the same page. The problem is that with the NameFormat, the fields have the same ID : $this->widgetSchema->setNameFormat('display[%s]'); Will display <form class="update_display_form" id="update_display_0" action="/iperf/web/frontend_dev.php/update_display" method="post"> <input type="checkbox" name="display[displayed]" checked="checked" id="display_displayed" /> <label for="display_displayed">test</label> </form> <form class="update_display_form" id="update_display_1" action="/iperf/web/frontend_dev.php/update_display" method="post"> <input type="checkbox" name="display[displayed]" checked="checked" id="display_displayed" /> <label for="display_displayed">truc</label> </form> And if you click on the second label, it will activate the first checkbox So I thought I could use the object id to make them unique : $this->widgetSchema->setNameFormat('display'.$this->getObject()->getId().'[%s]'); But then I can not process the request, since I don't know the name of the parameters. The best option I found was to set an ID : $this->widgetSchema['displayed']->setAttributes(array("id" => "display".$this->getObject()->getId() )); but then I totally loose the connections between the label and the checkbox. The problem would be solved if I could change the "for" attribute of my label. Does somebody know how to do that ? Or any other option ?

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• OUTPUT DID NOT REDIRECT TO THE INTENDED FILE OPENED FOR..

  - by rockyurock

  HELLO ALL, I USED THE BELOW CODE FOR CAPTURING THE OUTPUT (BELOW IN lines) IN A FILE "my_output.txt" BUT FAILED TO CAPTURE. **************output*************** inside value loop ------------------------------------------------------------ Server listening on UDP port 5001 Receiving 1470 byte datagrams UDP buffer size: 108 KByte (default) ------------------------------------------------------------ [ 3] local 192.168.16.2 port 5001 connected with 192.168.16.1 port 3189 [ ID] Interval Transfer Bandwidth Jitter Lost/Total Datagrams [ 3] 0.0- 5.0 sec 2.14 MBytes 3.61 Mbits/sec 0.369 ms 0/ 1528 (0%) inside value loop3 clue1 clue2 inside value loop4 one iperf completed *************************************** however when i enabled the local *STDOUT; in below code then i could see the above output on command prompt display (ofcourse server is sending some data). could anybody suggest me how can i capture the o/p in a file intended? below is the code i am using .. my $file = 'my_output.txt'; use Win32::Process; print"inside value loop\n"; # redirect stdout to a file #local *STDOUT; open STDOUT, '>', $file or die "can't redirect STDOUT to <$file> $!"; Win32::Process::Create(my $ProcessObj, "D:\\IOT_AUTOMATION_UTILITY\\_SATURDAY_09-04-10\\adb_cmd.bat", "adb shell /data/app/iperf -u -s -p 5001", 0, NORMAL_PRIORITY_CLASS, ".") || die ErrorReport(); #$alarm_time = $IPERF_RUN_TIME+10; #20sec #$ProcessObj->Wait(40); #print"inside value loop2\n"; #sleep $alarm_time; sleep 40; $ProcessObj->Kill(0); sub ErrorReport{ print Win32::FormatMessage( Win32::GetLastError() ); } /rocky

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• How do I redirect standard output to a file in Perl? [closed]

  - by rockyurock

  I want to send standard output to the file "my_output.txt" but failed. Here's the output: inside value loop ------------------------------------------------------------ Server listening on UDP port 5001 Receiving 1470 byte datagrams UDP buffer size: 108 KByte (default) ------------------------------------------------------------ [ 3] local 192.168.16.2 port 5001 connected with 192.168.16.1 port 3189 [ ID] Interval Transfer Bandwidth Jitter Lost/Total Datagrams [ 3] 0.0- 5.0 sec 2.14 MBytes 3.61 Mbits/sec 0.369 ms 0/ 1528 (0%) inside value loop3 clue1 clue2 inside value loop4 one iperf completed *************************************** When I enable the local *STDOUT; in below code then I could see the above output on command prompt display (ofcourse server is sending some data): my $file = 'my_output.txt'; use Win32::Process; print"inside value loop\n"; # redirect stdout to a file #local *STDOUT; open STDOUT, '>', $file or die "can't redirect STDOUT to <$file> $!"; Win32::Process::Create(my $ProcessObj, "D:\\IOT_AUTOMATION_UTILITY\\_SATURDAY_09-04-10\\adb_cmd.bat", "adb shell /data/app/iperf -u -s -p 5001", 0, NORMAL_PRIORITY_CLASS, ".") || die ErrorReport(); #$alarm_time = $IPERF_RUN_TIME+10; #20sec #$ProcessObj->Wait(40); #print"inside value loop2\n"; #sleep $alarm_time; sleep 40; $ProcessObj->Kill(0); sub ErrorReport{ print Win32::FormatMessage( Win32::GetLastError() ); }

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• The ping response time doesn't reflect the real network response time

  - by yangchenyun

  I encountered a weird problem that the response time returned by ping is almost fixed at 98ms. Either I ping the gateway, or I ping a local host or a internet host. The response time is always around 98ms although the actual delay is obvious. However, the reverse ping (from a local machine to this host) works properly. The following is my route table and the result: route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.1.1 0.0.0.0 UG 100 0 0 eth1 60.194.136.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth1 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1 # ping the gateway ping 192.168.1.1 PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. 64 bytes from 192.168.1.1: icmp_req=1 ttl=64 time=98.7 ms 64 bytes from 192.168.1.1: icmp_req=2 ttl=64 time=97.0 ms 64 bytes from 192.168.1.1: icmp_req=3 ttl=64 time=96.0 ms 64 bytes from 192.168.1.1: icmp_req=4 ttl=64 time=94.9 ms 64 bytes from 192.168.1.1: icmp_req=5 ttl=64 time=94.0 ms ^C --- 192.168.1.1 ping statistics --- 5 packets transmitted, 5 received, 0% packet loss, time 4004ms rtt min/avg/max/mdev = 94.030/96.149/98.744/1.673 ms #ping a local machine ping 192.168.1.88 PING 192.168.1.88 (192.168.1.88) 56(84) bytes of data. 64 bytes from 192.168.1.88: icmp_req=1 ttl=64 time=98.7 ms 64 bytes from 192.168.1.88: icmp_req=2 ttl=64 time=96.9 ms 64 bytes from 192.168.1.88: icmp_req=3 ttl=64 time=96.0 ms 64 bytes from 192.168.1.88: icmp_req=4 ttl=64 time=95.0 ms ^C --- 192.168.1.88 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3003ms rtt min/avg/max/mdev = 95.003/96.696/98.786/1.428 ms #ping a internet host ping google.com PING google.com (74.125.128.139) 56(84) bytes of data. 64 bytes from hg-in-f139.1e100.net (74.125.128.139): icmp_req=1 ttl=42 time=99.8 ms 64 bytes from hg-in-f139.1e100.net (74.125.128.139): icmp_req=2 ttl=42 time=99.9 ms 64 bytes from hg-in-f139.1e100.net (74.125.128.139): icmp_req=3 ttl=42 time=99.9 ms 64 bytes from hg-in-f139.1e100.net (74.125.128.139): icmp_req=4 ttl=42 time=99.9 ms ^C64 bytes from hg-in-f139.1e100.net (74.125.128.139): icmp_req=5 ttl=42 time=99.9 ms --- google.com ping statistics --- 5 packets transmitted, 5 received, 0% packet loss, time 32799ms rtt min/avg/max/mdev = 99.862/99.925/99.944/0.284 ms I am running iperf to test the bandwidth, the rate is quite low for a LAN connection. iperf -c 192.168.1.87 -t 50 -i 10 -f M ------------------------------------------------------------ Client connecting to 192.168.1.87, TCP port 5001 TCP window size: 0.06 MByte (default) ------------------------------------------------------------ [ 4] local 192.168.1.139 port 54697 connected with 192.168.1.87 port 5001 [ ID] Interval Transfer Bandwidth [ 4] 0.0-10.0 sec 6.12 MBytes 0.61 MBytes/sec [ 4] 10.0-20.0 sec 6.38 MBytes 0.64 MBytes/sec [ 4] 20.0-30.0 sec 6.38 MBytes 0.64 MBytes/sec [ 4] 30.0-40.0 sec 6.25 MBytes 0.62 MBytes/sec [ 4] 40.0-50.0 sec 6.38 MBytes 0.64 MBytes/sec [ 4] 0.0-50.1 sec 31.6 MBytes 0.63 MBytes/sec

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• How passively monitor for tcp packet loss? (Linux)

  - by nonot1

  How can I passively monitor the packet loss on TCP connections to/from my machine? Basically, I'd like a tool that sits in the background and watches TCP ack/nak/re-transmits to generate a report on which peer IP addresses "seem" to be experiencing heavy loss. Most questions like this that I find of SF suggest using tools like iperf. But, I need to monitor connections to/from a real application on my machine. Is this data just sitting there in the Linux TCP stack?

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• Generate a limited amount of random network traffic between 2 hosts

  - by Andrew S

  I'm trying to find a utility that will allow me to generate a constant flow of random network traffic at a specified rate between 2 hosts. The utility needs to run on Windows and OSX. I've tried iperf but it seems to be more oriented toward short-term testing/statistics and it really taxes the CPU even at slower rates. I want something that will generate traffic for a few weeks at say 10Mbps while I use other tools to monitor the impact of that level of traffic on the network.

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• Suspected network performance issue on VirtualBox Ubuntu guest on Win7 host

  - by Adam

  I set up Ubuntu 12.04 in VirtualBox on the Win7 machine I was allocated on my new project. I am running Java, Eclipse, Tomcat to develop a large data-intensive application and I noticed that this application runs at half the speed of my colleague's identical machine, where he runs it all under Windows. I think I have narrowed down the performance issue to the network, after comparing and equalising all the Java VM settings with my colleague. Is there a ping test I can do or some other network diagnostic test to flag up any problems? To give some background, the network performance is confusing. Running a network speed test to my colleague's machine with iperf shows speeds of 6 Mb/s from my Ubuntu guest, and 90 Mb/s from the win7 host. Large downloads, e.g. the Java SDK, come down at about 1.2 MB/s on both the guest and the host. Pings are sub-1ms on the host, but 1.5ms on the guest. I also did a broadband speed test, and got 10Mb/s download speed on both, but the host has an upload speed of 10Mb/s but the guest only uploads at 3Mb/s. I've been trying to diagnose any MTU problems with ping -M do to identify any kind of packet fragmentation problem but it's progressing very slow because I don't have much experience in this area. From what I read on other people's networking issues with VB and Linux guests on Win7 hosts, I should be able to get the speed on the guest up to the same level as the host. I installed a fresh VM with Ubuntu again to see if I'd foobar'd it somehow, but I'm getting the same readings with iperf on the virgin installation. My setup is: Adapter 1: Intel PRO/1000 MT Desktop (NAT) Adapter 2: ditto (host-only adapter) eth0 Link encap:Ethernet HWaddr 08:00:27:0b:76:bf inet addr:10.0.2.15 Bcast:10.0.2.255 Mask:255.255.255.0 inet6 addr: fe80::a00:27ff:fe0b:76bf/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:86236 errors:0 dropped:0 overruns:0 frame:0 TX packets:49369 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:69163946 (69.1 MB) TX bytes:3530535 (3.5 MB) eth2 Link encap:Ethernet HWaddr 08:00:27:a3:26:b8 inet addr:192.168.56.101 Bcast:192.168.56.255 Mask:255.255.255.0 inet6 addr: fe80::a00:27ff:fea3:26b8/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:59 errors:0 dropped:0 overruns:0 frame:0 TX packets:57 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:9148 (9.1 KB) TX bytes:7648 (7.6 KB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:701 errors:0 dropped:0 overruns:0 frame:0 TX packets:701 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:66321 (66.3 KB) TX bytes:66321 (66.3 KB)

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• Maximise network transfer speed of various applications

  - by Alex

  When using nc, scp, wget to transfer files between 2 machines on a dedicated 2Mbps link, I get speeds between 0.5 and 1 Mbps. However, when I use iperf -c 10.0.1.4 -t 20 -P 12 (for example) I can maximise the speed of the link (getting stable 2Mbps). Is there a way to make single stream transfers (such as those done by scp) to utilise all/most of the link? Some kind of tcp settings, or iptables...?

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• Slow WLAN file transfer between server and tablet

  - by user266985

  My file server is running Ubuntu 12.04 and I'm sharing files from it over samba. It is connected via gigabit ethernet. My desktop, running Windows 8.1, is also connected via gigabit ethernet. I can transfer files between the two and completely saturate that gigabit pipe. However, I just got a Surface Pro 2, and I'm trying to stream HD movies from my server to the device over WiFi. For some reason, I can't break much past 1.5MB/s transferring files over the network. I've tried streaming through XBMC and a standard file copy; no difference. To add the confusion, if I connect to my guest network and then use my VPN server (installed on the router) to access the file server, I get around 3.2MB/s. I've been running diagnostics to determine the root and I think I've found it but I have no idea what is causing it or how to fix it. Router: Asus RT-N66U Surface Pro 2 Network Card: Marvell Avastar 350N (Driver 19/09/2013 v14.69.24044.150) InSSIDer: Link Score: 100 Co-Channels: 0 Overlapping: 0 5GHz Network Channel: 48+44 iperf File Server as Server; Surface Pro 2 as Client - TCP Performance: Acceptable ------------------------------------------------------------ Server listening on TCP port 5001 TCP window size: 85.3 KByte (default) ------------------------------------------------------------ [ 4] local 192.168.0.90 port 5001 connected with 192.168.0.56 port 57367 [ ID] Interval Transfer Bandwidth [ 4] 0.0- 1.0 sec 10.1 MBytes 84.7 Mbits/sec [ 4] 1.0- 2.0 sec 10.4 MBytes 87.6 Mbits/sec [ 4] 2.0- 3.0 sec 10.6 MBytes 88.8 Mbits/sec [ 4] 3.0- 4.0 sec 10.7 MBytes 89.5 Mbits/sec [ 4] 4.0- 5.0 sec 10.1 MBytes 84.4 Mbits/sec [ 4] 5.0- 6.0 sec 10.2 MBytes 85.8 Mbits/sec [ 4] 6.0- 7.0 sec 7.04 MBytes 59.1 Mbits/sec [ 4] 7.0- 8.0 sec 10.8 MBytes 90.2 Mbits/sec [ 4] 8.0- 9.0 sec 10.6 MBytes 89.1 Mbits/sec [ 4] 9.0-10.0 sec 8.62 MBytes 72.3 Mbits/sec [ 4] 0.0-10.0 sec 99.2 MBytes 83.1 Mbits/sec iperf Surface Pro 2 as Server, File Server as Client Performance: Poor ------------------------------------------------------------ Client connecting to 192.168.0.56, TCP port 5001 TCP window size: 22.9 KByte (default) ------------------------------------------------------------ [ 3] local 192.168.0.90 port 40233 connected with 192.168.0.56 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0- 1.0 sec 1.50 MBytes 12.6 Mbits/sec [ 3] 1.0- 2.0 sec 1.50 MBytes 12.6 Mbits/sec [ 3] 2.0- 3.0 sec 1.50 MBytes 12.6 Mbits/sec [ 3] 3.0- 4.0 sec 1.25 MBytes 10.5 Mbits/sec [ 3] 4.0- 5.0 sec 1.62 MBytes 13.6 Mbits/sec [ 3] 5.0- 6.0 sec 1.50 MBytes 12.6 Mbits/sec [ 3] 6.0- 7.0 sec 1.38 MBytes 11.5 Mbits/sec [ 3] 7.0- 8.0 sec 1.50 MBytes 12.6 Mbits/sec [ 3] 8.0- 9.0 sec 1.50 MBytes 12.6 Mbits/sec [ 3] 9.0-10.0 sec 1.62 MBytes 13.6 Mbits/sec [ 3] 0.0-10.1 sec 15.0 MBytes 12.4 Mbits/sec For some reason, it gets capped and I haven't got a clue why. Any suggestions? Edit: My link speed is reported as 270Mbps by Windows. I'm less than two metres from the router with a clear line of sight.

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• length of captured packets more than MTU

  - by kumar

  Hi, I m running iperf between two machines (linux) and I can observe the mtu of both the interfaces connected is 1500. I ran tcpdump to capture packets and I observed some packets have "length as 2962"....how come this is possible with mtu as only 1500? Please clarify. Thanks! Note: flags field is set as DF. and proto is TCP

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• Network Transfer Rate on SMB/FTP

  - by Jack Sleight

  Hi, We're trying to optimise our network transfer rate from the client PCs to the file server, but having no luck. If I run an iperf test between a client PC (Windows XP) and our server (Linux) with a large TCP window size (the default is 8kb) I can get 60 Mbps. But when I run an SMB transfer speed test all I get is around 35 Mbps. When I run an FTP transfer speed test all I get is around 32 Mbps. I thought this was to do with the TCP window size, but I have now increased that to 256960 and it made no difference at all. Any ideas what I'm doing wrong? Or is 35 Mbps all I should expect? Cheers, Jack

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• Force local IP traffic to an external interface

  - by calandoa

  I have a machine with several interfaces that I can configure as I want, for instance: eth1: 192.168.1.1 eth2: 192.168.2.2 I would like to be able to forward all the traffic to one of these local address trhough the other interface. For instance, all requests to an iperf, ftp, http server at 192.168.1.1 are not just routed internally, but forwarded through eth2 (and the external network will take care of re-routing the packet to eth1). I tried and looked at several commands, like iptables, ip route, etc... but nothing worked. The closest behavior I could get was done with: ip route change to 192.168.1.1/24 dev eth2 which send all 192.168.1.x on eth2, except for 192.168.1.1 which is still routed internally. The goal of this setup is to do interface driver testing without using two PCs. I am using Linux, but if you know how to do that with Windows, I'll buy it!

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• Just how slow should my VPN be?

  - by David Heggie

  I have a VPN setup between a remote office with 2 ADSL connections (8Mb downstream, 512Kb upstream) and a main office with a 10Mb EFM connection (10Mb both up and down). The VPN is an IPSec connection using a DrayTek 2930 router for the ADSL and a DrayTek 3200 router at the EFM end. However, I'm unable to get speeds over this connection (tested with iperf) of anything over 600Kb or so down from the main office (traffic will pretty much always be from the main office to the remote office) Whilst I realise that there is an overhead and I'm never going to get the "full" bandwidth available over this VPN, I'd like to think that there's something I should be looking at that may help improve it. I've tried using the DrayTek's built-in "VPN Trunking" features which are supposed to load-balance connections, but this doesn't seem to improve matters much. I guess my question is - is this the kind of performance I should expect from this kind of setup and I'll just have to live with it, or should I be able to squeeze something more out of it through some VPN magic?

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• What are good and bad jitter times for a LAN

  - by garyb32234234

  Ive just ran jperf (frontend to iperf) on our network between 2 workstations, its recorded jitter between 0.033ms and 0.048ms. Is this good or bad? Are there more variables that i would need to consider to make the decision? EDIT: TCP/IP Ethernet LAN 43 PCs 1 server, 100Mbits main switch, various small 8 port switches, test was done using UDP, Its a Windows Domain. I want to instal a few voip softphones on the workstations, see how many i can use that reliably work, im testing a few different workstations around the network to see where the best quality network paths are. Will also change some equipment if i identify bad connections.

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• Poor TCP loopback throughput on Windows

  - by Yodan Tauber

  I measured the throughput of a locally bound TCP socket connection on my computer (Intel Q9550, 64 GB RAM, Windows XP 64 bit) using iperf. I got dissatisfying results (around 1.6 Gbit/s) each time, no matter how I tweaked the TCP settings (buffer length, window size, max segment size, no delay). I got similar results when I tried netperf. Now, I understand (from sources like these) that the average throughput of a loopback connection should be around 5 Gbit/s. What could be the reasons for such poor performance?

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• Tips for debugging Samba performance?

  - by j-g-faustus

  Samba gives me 24 MB/s read and 44 MB/s write, while ftp gives 97 and 112 MB/s under the same circumstances. The documentation says that Generally, you should find that Samba performs similarly to ftp at raw transfer speed. In my case it clearly doesn't. Where can I find tips on how to debug Samba performance? Or alternatively tips for replacing Samba with something else? (I can't use ftp, unfortunately, as I need something that can be used with rsync/rsnapshot.) More details: Both computers are running Ubuntu 10.10 (using Samba because I have a Mac as well) The Samba share is on a local home network, mounted as $ mount ... //server.local/share/ on /mnt/share type cifs (rw,mand) Samba performance was tested by copying (cp) a single file of ~4GB to and from the share, using time for timing and calculating transfer speed by hand. ftp performance are the numbers from the ftp client for get/put of the same file. iperf gives network speed ~900 Mbits/s bonnie++ gives disk speeds 200 MB/s on both sides for block reads as well as block writes Tried changing the parameters suggested in the performance tuning HOWTO (read/write raw, read size, socket options), most of them made little to no difference. (The one that made a difference caused write speed to drop 50%.)

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