I have a question in order to understand how iperf is working, I am using the following command.
What i dont understand is "How can 6945 datagrams are send?" because if 9.66 MBytes are transfered, then 9.66M/1458 = 6625 data grams should be tranfereded according to my understanding.
If 10.125MBytes (2.7Mbps * 30 sec) would have been transfered then 6944 data grams would have been send (excluding udp and other header)
Please clerify if some one knows ..
(Also I have used wireshark on both client and server and checked and there the number of packets is greater then the number of packets shown by iperf)
umar#umar-VPCEB11FM:~$ iperf -t 30 -c 192.168.3.181 -u -b 2.7m -l 1458
------------------------------------------------------------
Client connecting to 192.168.3.181, UDP port 5001
Sending 1458 byte datagrams
UDP buffer size: 208 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.3.175 port 47241 connected with 192.168.3.181 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-30.0 sec 9.66 MBytes 2.70 Mbits/sec
[ 3] Sent 6946 datagrams
[ 3] Server Report:
[ 3] 0.0-92318.4 sec 9.66 MBytes 878 bits/sec 0.760 ms 0/ 6945 (0%)
iperf uses base 2 for M and K, meaning that K = 1024 and M = 1024*1024.
When you do that math that way, you get 9.66 MB / 1458 B/d = 6947 datagrams which is within precision error (you have a max resolution of 0.01 MB which means a rounding error of 0.005 MB ~= 3.6 datagrams).
Related
Currently I am capturing network packets using tcpreplay at a speed of 800 MBPS but I want to scale it over 5 GBPS.
I am running Joy on a server with 16GB Ram and 8 Cores
Tcpreplay Output:
`Actual: 2427978 packets (2098973496 bytes) sent in 20.98 seconds
Rated: 100003501.6 Bps, 800.02 Mbps, 115678.59 pps
Flows: 49979 flows, 2381.11 fps, 2426216 flow packets, 1756 non-flow
Statistics for network device: vth0
Successful packets: 2427978
Failed packets: 0
Truncated packets: 0
Retried packets (ENOBUFS): 0
Retried packets (EAGAIN): 0`
Total Packets Captured: 2412876
I am running Joy on 4 threads but even if I use 24 threads I am not able to see any drastic change in the capturing or receiving speed.
Joy is using af_packet with Zero Copy Ring Buffer and even Cisco mercury use the same mechanism to write packets but they claim that Mercury can write at 40 GBPS on a server-class hardware so anyone have any suggestion on this issue then please revert back.
iperf2 (version 2.0.9) reports latency in its output as shown below.
Is it a two-way latency or one-way latency measurement ?
Server listening on UDP port 5001 with pid 5167
Receiving 1470 byte datagrams
UDP buffer size: 208 KByte (default)
[ 3] local 192.168.1.102 port 5001 connected with 192.168.1.101 port 59592
[ ID] Interval Transfer Bandwidth Jitter Lost/Total Latency avg/min/max/stdev PPS
[ 3] 0.00-1.00 sec 122 KBytes 1.00 Mbits/sec 0.063 ms 0/ 6254 (0%) 659.932/659.882/660.502/ 8.345 ms 6252 pps
[ 3] 1.00-2.00 sec 122 KBytes 1.00 Mbits/sec 0.020 ms 0/ 6250 (0%) 660.080/659.919/666.878/ 0.110 ms 6250 pps
[ 3] 2.00-3.00 sec 122 KBytes 1.00 Mbits/sec 0.020 ms 0/ 6250 (0%) 660.113/659.955/660.672/ 0.047 ms 6250 pps
[ 3] 3.00-4.00 sec 122 KBytes 1.00 Mbits/sec 0.022 ms 0/ 6250 (0%) 660.153/659.994/660.693/ 0.047 ms 6250 pps
[ 3] 4.00-5.00 sec 122 KBytes 1.00 Mbits/sec 0.021 ms 0/ 6250 (0%) 660.192/660.034/660.617/ 0.049 ms 6250 pps
It's one-way which requires the clocks to be synchronized to a common reference. You may want to check in to Precision Time Protocol. Also, tell your hosting provider that you want better clocks in their data centers. The GPS atomic clock is quite accurate and the signal is free.
There is a lot more work going on with iperf 2.0.14 related to TCP write to read latencies. Version 2.0.14 will enforce the use of --trip-times on the client before any end/end or one way latency measurements are presented. This way the user tells iperf that the systems have their clocks synchronized to the accuracy which the user deems as sufficient. We also produce a Little's law inP metric along with network power. See the man pages for more. The hope is to have iperf 2.0.14 released by early 2021.
[rjmcmahon#localhost iperf2-code]$ src/iperf -s -i 1
[ 4] local 192.168.1.10%enp2s0 port 5001 connected with 192.168.1.80 port 47420 (trip-times) (MSS=1448) (peer 2.0.14-alpha)
[ ID] Interval Transfer Bandwidth Reads Dist(bin=16.0K) Burst Latency avg/min/max/stdev (cnt/size) inP NetPwr
[ 4] 0.00-1.00 sec 1.09 GBytes 9.34 Gbits/sec 18733 2469:2552:2753:2456:2230:2272:1859:2142 2.988/ 0.971/ 3.668/ 0.370 ms (8908/131072) 3.34 MByte 390759.84
Note: For my testing during iperf 2 development, I have GPS disciplined oven controlled oscillators from spectracom in my systems. These cost about $2.5K each and require a GPS signal.
As you can see in the below command I have assigned a total of 500 GB disk space to my VM. But I am seeing 14.4 GB actual space available to the disk and once it gets used completely. I got an error there isn't much space to use? How to extend space for /dev/mapper/centos-root.
I am using VMware ESXi and using centOS for this VM.
[root#localhost Apr]# fdisk -l
Disk /dev/sda: 536.9 GB, 536870912000 bytes, 1048576000 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x00064efd
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 33554431 15727616 8e Linux LVM
Disk /dev/mapper/centos-root: 14.4 GB, 14382268416 bytes, 28090368 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/centos-swap: 1719 MB, 1719664640 bytes, 3358720 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 byte
Execute bellow Steps to increase your Linux Disk after adding space in VMWare :
Step 1 - update partition table
fdisk /dev/sda
Press p to print the partition table to identify the number of partitions.
Press n to create a new primary partition.
Press p for primary.
Press 3 for the partition number, depending on the output of the partition table print.
Press Enter two times.
Press t to change the system's partition ID.
Press 3 to select the newly creation partition.
Type 8e to change the Hex Code of the partition for Linux LVM.
Press w to write the changes to the partition table.
Step 2 - Restart the virtual machine.
Step 3 - verify that the changes were saved
fdisk -l
Step 4 - convert the new partition to a physical volume
pvcreate /dev/sda3
Step 5 - extend the physical volume (centos is your VG name, if not use your VG name in place of centos )
vgextend centos /dev/sda3
Step 6 - extend the Logical Volume (500G is the size you want to add , if not use the right size in place of 500G)
lvextend -L+500G /dev/mapper/centos-root
Step 7 - expand the ext filesystem online
resize2fs /dev/mapper/centos-root
extend disk without reboot
echo 1 > /sys/block/sda/device/rescan
echo 1 > /sys/block/sdb/device/rescan
echo 1 > /sys/block/nvme0n1/device/rescan_controller
partprobe
gdisk fix warnging
parted change partion size
## parted can executed as command line. but this is very dangerous
parted -s /dev/sdb "resizepart 2 -1" quit
parted -s /dev/sdb "resizepart 3 100%" quit
resizepart 3 100%
pvresize /dev/sda3
lvextend -l +100%FREE cs/root
xfs_growfs /dev/cs/root
I am very newbie in OrangePI PC. I have installed it by dd on my macOS, and I have tried installing a Raspbian image which downloaded from the orangepi.org in Windows as well, after installation when I check free disk space it is showing:
root#orangepi:~# df -h
Filesystem Size Used Avail Use% Mounted on
rootfs 3.4G 2.7G 474M 86% /
/dev/root 3.4G 2.7G 474M 86% /
devtmpfs 374M 0 374M 0% /dev
tmpfs 101M 188K 101M 1% /run
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 201M 0 201M 0% /run/shm
/dev/mmcblk0p1 41M 4.9M 37M 12% /boot
I have installed it on 32G flash drive. But when I check it through fdisk command it shows 32G as a disk size:
root#orangepi:~# sudo fdisk -l
Disk /dev/mmcblk0: 32.0 GB, 32010928128 bytes
4 heads, 16 sectors/track, 976896 cylinders, total 62521344 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x34605ba5
Device Boot Start End Blocks Id System
/dev/mmcblk0p1 40960 124927 41984 83 Linux
/dev/mmcblk0p2 124928 7170047 3522560 83 Linux
root#orangepi:~#
How to fix this?
This solved my problem (solution is taken from here):
root#orangepi:~# fdisk /dev/mmcblk0
Command (m for help): p
Disk /dev/mmcblk0: 15.8 GB, 15804137472 bytes
4 heads, 16 sectors/track, 482304 cylinders, total 30867456 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x34605ba5
Device Boot Start End Blocks Id System
/dev/mmcblk0p1 40960 124927 41984 83 Linux
/dev/mmcblk0p2 124928 7170047 3522560 83 Linux
Command (m for help): d
Partition number (1-4): 2
Command (m for help): n
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p): p
Partition number (1-4, default 2): 2
First sector (2048-30867455, default 2048): 124928
Last sector, +sectors or +size{K,M,G} (124928-30867455, default 30867455):
Using default value 30867455
Command (m for help): w
Then quit (command q), reboot. You will then be able to use resize:
resize2fs /dev/root
I am using iperf and have the following problem
iperf ... -b 60M, I have 12% packet loss
iperf ... -b 60m, I have 0.2% packet loss
In both of these cases, the bandwidth is 60 Mbit/s
0.0-10.0 sec 71.0 MBytes 59.6 Mbits/sec 0.150 ms 0/50661 (0%)
What is the difference between -b 60m and -b 60M ?
I found the answer after hours of searching:
m = 1000*1000 bit
M = 1024*1024 bit
I have problem with searching for interpreting the result of iperf ( I am doing testing on boards and sometimes the result do not follow ordinary patterns).
Does anyone knows of any good website or document?