Why is the data transfer rate via NFS and Samba protocols inside a local Wi-Fi network so low?

Question

linux

Hardware:
Desktop (Ubuntu 14.04) with network card :

[email protected]:~$ lspci | grep Network
07:00.0 Network controller: Qualcomm Atheros AR9485 Wireless Network Adapter (rev 01)

Laptop (Ubuntu 14.04) with network card:

[email protected]:~$ lspci | grep Network
04:00.0 Network controller: Qualcomm Atheros AR9285 Wireless Network Adapter (PCI-Express) (rev 01)

And a router . All three components support the 801.22n standard and a theoretical throughput of 150 Mbps.
Now the facts: from a laptop to a desktop (or vice versa), I transfer a large file (several gigabytes).

And the maximum speed at 150 Mbps is a little over 2 Mb , both for Samba and NFS.
desktop iwconfig:

[email protected]:~$ iwconfig
eth0      no wireless extensions.

lo        no wireless extensions.

wlan0     IEEE 802.11bgn  ESSID:"bububu"  
          Mode:Managed  Frequency:2.437 GHz  Access Point: F8:1A:67:4E:5B:70   
          Bit Rate=150 Mb/s   Tx-Power=20 dBm   
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality=35/70  Signal level=-75 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:30  Invalid misc:609   Missed beacon:0

laptop iwconfig:

[email protected]:~$ iwconfig
eth0 no wireless extensions.

lo no wireless extensions.

wlan0 IEEE 802.11bgn ESSID:"bububu" 
Mode:Managed Frequency:2.437 GHz Access Point: F8:1A:67:4E:5B:70 
Bit Rate=150 Mb/s Tx-Power=15 dBm 
Retry long limit:7 RTS thr:off Fragment thr:off
Power Management:off
Link Quality=51/70 Signal level=-59 dBm 
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:86 Missed beacon:0

I read all sorts of different things, tried to give some parameters to samba, see if the channel was clogged with neighbors, saw authoritative opinions about duplex modes and that the channel would actually work a maximum of a third of 150 Mbps, and even this duplex should be divided into two ... In general, everything around is replete with opinions, the sense of which is zero. I am not going to sit down and read Tannenbaum, I immediately ask such advisers to go through the forest.
From you, dear tipsters, I would like to hear the following advice: what speed can you really reach with such equipment and why is everything limited to such a speed ceiling? In the very near future, I want a home file washer, and such a data transfer rate does not fit into it (I realize that you can replace the desktop network card and router and buy a new laptop).
UPD. Resultiperf -s и iperf -c <ip компа с iperf -s>

[email protected]:~$ iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.0.101 port 5001 connected with 192.168.0.100 port 56877
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.1 sec 29.8 MBytes 24.6 Mbits/sec
[ 5] local 192.168.0.101 port 5001 connected with 192.168.0.100 port 56878
[ 5] 0.0-10.1 sec 34.8 MBytes 28.8 Mbits/sec
[ 4] local 192.168.0.101 port 5001 connected with 192.168.0.100 port 56879
[ 4] 0.0-10.1 sec 39.6 MBytes 32.9 Mbits/sec
[ 5] local 192.168.0.101 port 5001 connected with 192.168.0.100 port 56880
[ 5] 0.0-10.2 sec 20.9 MBytes 17.1 Mbits/sec
[ 4] local 192.168.0.101 port 5001 connected with 192.168.0.100 port 56881
[ 4] 0.0-10.2 sec 20.9 MBytes 17.2 Mbits/sec
[ 5] local 192.168.0.101 port 5001 connected with 192.168.0.100 port 56882
[ 5] 0.0-10.3 sec 23.6 MBytes 19.3 Mbits/sec
[ 4] local 192.168.0.101 port 5001 connected with 192.168.0.100 port 56883
[ 4] 0.0-10.5 sec 23.6 MBytes 18.9 Mbits/sec
[ 5] local 192.168.0.101 port 5001 connected with 192.168.0.100 port 56886
[ 5] 0.0-10.2 sec 17.4 MBytes 14.3 Mbits/sec
[ 4] local 192.168.0.101 port 5001 connected with 192.168.0.100 port 56887
[ 4] 0.0-10.2 sec 26.2 MBytes 21.7 Mbits/sec
[ 5] local 192.168.0.101 port 5001 connected with 192.168.0.100 port 56888
[ 5] 0.0-10.2 sec 37.1 MBytes 30.6 Mbits/sec

The average speed is 22.54 Mbps, which is equal to 2.82 MB/s. So the problem is in the network, not in the protocols. What to do?

Answer 1

Link Quality=35/70 Signal level=-75 dBm

It's kind of dumb.
I accelerate somewhere up to 4.5 MB / s on such a network:

wlan0     IEEE 802.11bgn  ESSID:"lion's den"  
          Mode:Managed  Frequency:2.412 GHz  Access Point: 78:54:2E:02:50:32   
          Bit Rate=65 Mb/s   Tx-Power=20 dBm   
          Retry  long limit:7   RTS thr=2347 B   Fragment thr:off
          Power Management:off
          Link Quality=70/70  Signal level=-40 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:1869   Missed beacon:0

Answer 2

And what do you actually want? Wireless technologies they are, they are very dependent on the quality of the signal. Either the router is directly accessible at a distance of 2-3 meters from the devices, or pull the wires.

Answer 3

Perhaps your frequency is very noisy and the router / card has to send a lot of unnecessary correction packets, which reduces network throughput. Try changing the network channels on the router or if there is software (unfortunately I don’t know what is available for this under ubuntu), you can scan your wifi range and see which channel is the least noisy and not busy with neighboring networks.

Answer 4

Hey! And what is the speed of the cable?
I ran into a problem on ubuntu 12.04 when copying files to mounted smb shares.
On the client (For speeding up slow samba shares changing smb.conf's socket options to the following worked):
vi /etc/samba/smb.conf

[global]
# Samba mounted with cifs or smbfs slow, but gvfs is fast. Use this
socket options = TCP_NODELAY SO_SNDBUF=4096 SO_RCVBUF=4096

Retrieved from ubuntuforums.org/showthread.php?t=1213688

Answer 5

The speed in samba is limited in the wifi network, the average speed will be 2Mb/sec. I don't know how to avoid this. But I know that if the server is needed only for copying data, I recommend setting up an FTP server. The speed in it on wifi is about 100 megabits. The standard ftp server is present in any windows.