Re: TCP data throughput for BCM43362

Hi Franky,

On Fr, 2016-08-05 at 17:56 -0700, Franky Lin wrote:

On Fri, Aug 5, 2016 at 2:29 PM, Jörg Krause <joerg.krause@embedded.ro
cks>
wrote:

quoted

Am 5. August 2016 23:01:10 MESZ, schrieb Arend Van Spriel <
arend.vanspriel@broadcom.com>:

quoted

Op 5 aug. 2016 22:46 schreef "Jörg Krause"
[off-list ref]:

quoted

Hi,

I'm using a custom ARM board with an BCM43362 wifi chip from

Broadcom.

quoted

The wifi chip is attached via SDIO to the controller with a
clock of
48MHz. Linux kernel version is 4.7.

When measuring the network bandwidth with iperf3 I get a
bandwith of
only around 5 Mbps. I found a similar thread at the Broadcom

community

quoted

[1] where the test was done with a M4 CPU + BCM43362 and an
average
result of 3.3 Mbps.

Interestingly, a BCM43362 Wi-Fi Dev Kit [2] notes a TCP data

throughput

quoted

greater than 20 Mbps.

Why is the throughput I measured much lower? Note that I
measured
several times with almost no neighbor devices or networks.

This is a test sample measured with iperf3:

    $ iperf3 -c 192.168.2.1 -i 1 -t 10
    Connecting to host 192.168.2.1, port 5201
    [  4] local 192.168.2.155 port 36442 connected to
192.168.2.1

port

quoted

    5201
    [ ID]
Interval           Transfer     Bandwidth       Retr  Cwnd
    [  4]   0.00-1.00   sec   615 KBytes  5.04
Mbits/sec    0   56.6
    KBytes
    [  4]   1.00-2.00   sec   622 KBytes  5.10
Mbits/sec    0   84.8
    KBytes
    [  4]   2.00-3.00   sec   625 KBytes  5.12
Mbits/sec    0    113
    KBytes
    [  4]   3.00-4.00   sec   571 KBytes  4.68
Mbits/sec    0    140
    KBytes
    [  4]   4.00-5.00   sec   594 KBytes  4.87
Mbits/sec    0    167
    KBytes
    [  4]   5.00-6.00   sec   628 KBytes  5.14
Mbits/sec    0    195
    KBytes
    [  4]   6.00-7.00   sec   619 KBytes  5.07
Mbits/sec    0    202
    KBytes
    [  4]   7.00-8.00   sec   608 KBytes  4.98
Mbits/sec    0    202
    KBytes
    [  4]   8.00-9.00   sec   602 KBytes  4.93
Mbits/sec    0    202
    KBytes
    [  4]   9.00-10.00  sec   537 KBytes  4.40
Mbits/sec    0    202
    KBytes
    - - - - - - - - - - - - - - - - - - - - - - - - -
    [ ID] Interval           Transfer     Bandwidth       Retr
    [  4]   0.00-10.00  sec  5.88 MBytes  4.93
    Mbits/sec    0             sender
    [  4]   0.00-10.00  sec  5.68 MBytes  4.76
    Mbits/sec                  receiver

Not overly familiar with iperf3. Do these lines mean you are
doing
bidirectional test, ie. upstream and downstream at the same time.
Another
thing affecting tput could be power-save.

No, iperf3 does not support bidrectional test. Power-save is turned
off.

What does iw link say?

It says:

# iw dev wlan0 link
Connected to xx:xx:xx:xx:xx (on wlan0)
	SSID: xxx
	freq: 2437
	signal: -60 dBm
	tx bitrate: 58.5 MBit/s

	bss flags:	short-preamble short-slot-time
	dtim period:	1
	beacon int:	100

Best regards
Jörg Krause